Resident Short Reviews
Endocrine Manifestations of von Hippel–Lindau Disease Clarissa Cassol, MD; Ozgur Mete, MD
von Hippel–Lindau (VHL) disease is an autosomal dominant disorder caused by heterozygous mutations in the VHL tumor suppressor gene that is characterized by the occurrence of multiple endocrine and nonendocrine lesions. This review focuses on the endocrine manifestations of VHL disease. Pancreatic neuroendocrine proliferations (ductuloinsular complexes, islet dysplasia, endocrine microadenoma, and neuroendocrine tumors), pheochromocytomas, and extra-adrenal paragangliomas are important endocrine manifestations of VHL disease. They frequently display characteristic clinical, biochemical, and histopathologic features that, although not pathognomonic, can be helpful in suggesting VHL disease as the underlying etiology and distinguishing these tumors from sporadic cases. Recent improvements in treatment and outcomes of renal cell carcinomas have allowed pancreatic neuroendocrine tumors to emerge as a significant source of metastatic disease, making the accurate recognition and classification of these neoplasms by the pathologist of utmost importance to determine prognosis, treatment, and follow-up strategies for affected patients. (Arch Pathol Lab Med. 2015;139:263–268; doi: 10.5858/ arpa.2013-0520-RS)
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hemangiomas of the adrenal gland, liver, and lung; and a variety of solid tumors, including clear cell renal carcinomas, pheochromocytomas, paragangliomas, pancreatic neuroendocrine tumors (NETs), endolymphatic sac tumors, and papillary tumors of the broad ligament or epididymis (papillary cystadenoma).1 VHL lesions develop following the classic Knudson 2-hit hypothesis in which secondary inactivation of the nonmutated VHL allele leads to loss of pVHL function. This results in failure of polyubiquitination and proteasomal degradation of HIF, which is central for the pathogenesis of the disease. The resulting high levels of HIF create a state of pseudohypoxia leading to transcriptional activation of genes linked to erythropoiesis, angiogenesis, and cell metabolism. This condition will contribute to the development of highly vascularized tumors typical of VHL and the commonly observed erythrocytosis in affected patients.1 Most recently, HIF-independent pVHL functions have also been uncovered that may play a role in VHL tumorigenesis. Those include apoptosis regulation, cell senescence control, microtubule stabilization and maintenance of the primary cilium, and regulation of extracellular matrix formation and cell-cell adhesion.2 Corroborating the role of VHL protein loss in the development of VHL-related tumors is the fact that some sporadic renal cell carcinomas, hemangioblastomas, and pheochromocytomas also harbor VHL biallelic inactivation.3 In this review, we will focus on the endocrine manifestations of VHL disease.
Accepted for publication November 18, 2013. From the Department of Pathology, University Health Network, Toronto, Ontario, Canada, and the Department of Laboratory Medicine and Pathobiology, University of Toronto, Ontario, Canada. The authors have no relevant financial interest in the products or companies described in this article. Reprints: Ozgur Mete, MD, Department of Pathology, University Health Network, 200 Elizabeth St, 11th Floor, Toronto, ON M5G 2C4, Canada (e-mail: [email protected]).
DIAGNOSIS AND CLINICAL FEATURES The incidence of VHL disease is estimated to be at least 1 per 36 000 individuals.1 The penetrance is age dependent, but reaches approximately 95% by age 65 years.1 In patients with a positive family history, a clinical diagnosis of VHL disease can be made by the finding of a single VHLassociated tumor.1 Approximately 20% of cases result from de novo mutations and therefore do not have a positive family history.2 In these cases the presence of at least 2 VHL-associated tumors is required for the diagnosis.1 Whenever a clinical diagnosis of VHL disease is suspected, individuals should be referred for genetic screening for VHL gene mutation detection. In the past, up to 20% of patients with a clinical diagnosis were reported to have no VHL mutations on screening; however, current improvements in genetic diagnosis make it possible to detect mutations in virtually all cases.2 Genotype-phenotype correlations form the basis for the clinical classification of VHL disease. Type 1 disease does not include pheochromocytoma as one of its features and is generally caused by whole or partial gene deletion or nonsense mutation, while type 2 disease is characterized by
he von Hippel–Lindau (VHL) disease (MIM 193300) is an autosomal dominant disorder caused by heterozygous mutations in the VHL tumor suppressor gene (3p25.3). The VHL gene encodes a 232-amino-acid protein (pVHL), which is essential in the regulation of the hypoxia-inducible factor (HIF)–1 and HIF-2 affecting the upregulation of vascular endothelial growth factor (VEGF), platelet-derived growth factor beta (PDGFb), transforming growth factor alpha (TGFa), and erythropoietin substances. While heterozygous VHL mutations cause VHL disease, homozygous mutations result in familial erythrocytosis-2 (ECYT2; 263400) (http://omim.org; accessed November 9, 2013). VHL disease is characterized by the occurrence of multiple nonendocrine and endocrine lesions, including hemangioblastomas of the retina, cerebellum, or spinal cord; visceral cysts (especially of the kidney, pancreas, and liver);
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severe upper gastrointestinal hemorrhage, duodenal stenosis, and/or cholangitis.8 The mean age at which pancreatic NETs are diagnosed in patients with VHL disease is lower than in sporadic cases (35 versus 58 years),6,9 which is probably due to periodic screening in these patients and may contribute to the better prognosis observed for VHL-associated NETs when compared to sporadic ones.10 As previously mentioned, pheochromocytomas occur only in type 2 VHL disease, accounting for 10% of all cases.3 Similar to pancreatic NETs, pheochromocytomas in patients with VHL also tend to be diagnosed at a younger age (approximately 20 years) than in sporadic cases (mean age at diagnosis, 43.9 years).10 They are usually bilateral adrenal, multiple, or extra-adrenal2 and can be asymptomatic.11 Malignant disease is relatively rare, at about 5% or lower, and head and neck tumors are infrequent.2
Figure 1. Gross features of von Hippel-Lindau (VHL)–related pancreatic neuroendocrine tumors and pheochromocytomas/extra-adrenal paragangliomas. Pancreatic neuroendocrine tumors associated with VHL disease are often multiple and are located throughout the pancreas. Grossly, they are well-demarcated, variegated, and brown to yellow tan masses (star), most commonly in the background of cystic disease. A, Grossly, the presence of a thick vascular tumor capsule has been suggested to be a distinctive feature of VHL-related pheochromocytomas or extra-adrenal paragangliomas. B, Arrows indicate the presence of thick tumor capsule.
the occurrence of pheochromocytomas and is associated with missense mutations. Type 2 disease can be further subdivided in type 2A (low risk of renal cell carcinoma), type 2B (high risk of renal cell carcinoma), and type 2C (pheochromocytoma only).2 Pancreatic lesions are common in VHL disease and often present with benign cystic disease including microcystic or serous adenomas, which occur in up to 70% of patients with VHL.1 These lesions rarely prompt a VHL diagnosis and are most often discovered incidentally during abdominal imaging screening.4 Simple cysts and serous cystadenomas have uncommonly been associated with symptoms of abdominal mass or obstructive jaundice, while pancreatic NETs are usually clinically nonfunctioning5 and can rarely present with abdominal pain, nausea, or diarrhea.6 Possible complications of these lesions include compression of the main pancreatic duct, leading to pancreatitis,7 and compression or invasion of adjacent organs, which can result in 264 Arch Pathol Lab Med—Vol 139, February 2015
GROSS PATHOLOGY Pancreatic NETs associated with VHL disease are often multiple and are located throughout the pancreas.6 Grossly, they are well-demarcated, variegated, and red-brown to yellow tan masses, most commonly in the background of cystic disease (Figure 1, A).4,6 A fibrotic focus, defined as a scarlike fibrosclerotic area located within the tumor and containing a variable number of fibroblasts admixed with collagen fibers, was observed in 76% of pancreatic NETs in 1 series.8 This feature has been shown to be associated with a worse prognosis in several other carcinomas and has been postulated to represent a hypoxic phenomenon in advanced tumors.8 VHL–related pheochromocytomas can be bilateral in up to 60% of cases.12 Grossly, the presence of a thick vascular tumor capsule has been suggested to be a distinctive feature of VHL-related pheochromocytomas or extra-adrenal paragangliomas (Figure 1, B).13,14 In 2 series of VHL-related pheochromocytomas, mean tumor sizes were 3.25 and 3.7 cm.12,13 HISTOPATHOLOGY The common endocrine manifestations of VHL disease include neuroendocrine neoplasms arising from adrenal medulla (pheochromocytoma) and extra-adrenal paraganglia (paraganglioma) along with pancreatic NETs. VHL– related pancreatic NETs and paragangliomas/pheochromocytomas will be discussed in detail in this section. Other rare neuroendocrine tumors reported in patients with VHL include clear cell NETs in the ampulla and gallbladder,15,16 a clinically functioning duodenal D cell NET,17 a NET of the common bile duct,18 an aggressive growth hormone– prolactin-producing pituitary adenoma,19 and a parathyroid adenoma with primary hyperparathyroidism.20 Pancreatic Neuroendocrine Proliferations Among patients with VHL disease who undergo abdominal imaging, up to 77% have some pancreatic lesion detected,7 most commonly pancreatic cysts, of which 86% are multiple5 (Figure 2, A). Serous microcystic adenomas (also known as serous cystadenomas) have been identified in approximately 10% of patients and are also frequently multiple.4 A pancreatic neuroendocrine proliferation reaching a size of 0.5 cm is termed a neuroendocrine tumor (NET). Pancreatic NETs have been described in 11% to 17% of patients with VHL disease.8 Similar to multiple endocrine neoplasia type 1 (MEN1) syndrome, patients with VHL VHL Disease—Cassol & Mete
Figure 2. Histopathologic and immunohistochemical features of neuroendocrine proliferations associated with von Hippel–Lindau (VHL) disease. Pancreatic pathologic features in VHL usually take the form of benign cysts (A), and pancreatic neuroendocrine tumors are less common. Similar to multiple endocrine neoplasia type 1 syndrome, VHL disease can be associated with precursor lesions including ductuloinsular complexes, islet dysplasia, pancreatic microadenomas (A; asterisk), and peliosis (B) of the nontumorous islets. von Hippel-Lindau–related pancreatic neuroendocrine tumors (NETs) can have solid, trabecular, or glandular architecture with stromal fibrosis (C). Both pancreatic NETs and pheochromocytomas/extraadrenal paragangliomas characteristically contain clear cells or multivacuolated lipid-rich cells in varying proportions (C and D) that can sometimes mimic signet ring cell carcinoma (E). These neoplasms can express peptide hormones. Pancreatic polypeptide–expressing, VHL-related pancreatic NET is illustrated in this example (F). Positivity for inhibin is used to suggest the possibility of VHL disease underlying multifocal clear cell neuroendocrine tumors (G). Positivity for tyrosine hydroxylase should be assessed to render a diagnosis of paraganglioma when dealing with a keratin-negative neuroendocrine neoplasm (H) (hematoxylin-eosin, original magnifications 32.5 [A], 340 [B and E], and 320 [C and D]; Pancreatic polypeptide, inhibin, and tyrosine hydroxylase, original magnifications, 320[ F, G, and H]). Arch Pathol Lab Med—Vol 139, February 2015
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disease can be associated with precursor lesions including ductuloinsular complexes (nesidioblastosis), islet dysplasia (referring to normal-sized or slightly enlarged islets ,0.5 mm that contain neuroendocrine cells showing loss of the normal spatial and quantitative arrangement of the normal a, b, d, and PP cell types), pancreatic microadenomatosis (when islet dysplasia is between 0.5–5 mm, it is termed microadenoma; multiple microadenomas are termed microadenomatosis), and peliosis of the nontumorous islets17 (Figure 2, A and B). Similar to other pancreatic NETs, VHL-related pancreatic NETs should be classified according to the 2010 World Health Organization (WHO) classification, which uses a 3tier grading system: grade 1 NET: Ki-67 of 2% or less and/or mitotic activity less than 2 mitoses per 10 high-power fields (HPFs); grade 2 NET: Ki-67: 3% to 20% and/or mitotic activity equal to 2 to 20 mitoses per 10 HPFs; and grade 3 neuroendocrine carcinoma: Ki-67 index greater than 20% and/or mitotic activity greater than 20 mitoses per 10 HPFs.21 VHL–related pancreatic NETs can have solid, trabecular, or glandular architecture. Prominent stromal collagen bands have been observed6 (Figure 2, C). These tumors are hypervascular5 and characteristically contain clear cells or multivacuolated lipid-rich cells in varying proportion15,17 (Figure 2, C and D) along with nuclear features characteristic of NETs. Clear cells in these tumors frequently coexist with lipid-containing foamy cells, and it has been suggested they are actually an exaggerated form of foamy cytoplasm with coalescence of small lipid vacuoles and the formation of a large vacuole that occupies the entire cytoplasm, thus creating an empty space.22 This phenomenon is also attributed to the activation of HIF1-a, leading to a status of pseudohypoxia resulting in lipid and glycogen accumulation in tumor cells.15 It has been shown that HIF-mediated stimulation of lipin 1 expression causes triglyceride accumulation.23 Furthermore, glycogen synthesis is induced in hypoxia by HIF-1 and promotes tumor cell survival.24 This phenomenon can sometimes mimic a signet ring cell carcinoma15 (Figure 2, E). These neoplasms are positive for chromogranin A and synaptophysin by immunohistochemistry and can be focally positive for somatostatin, pancreatic polypeptide (Figure 2, F), vasoactive intestinal peptide, insulin, and/or glucagon.6 Interestingly, none have shown gastrin positivity,6 which is in contrast with MEN1-associated NETs, which are gastrin producing in up to 50% of cases.17 Interestingly, inhibin positivity has been reported in clear cell NETs associated with VHL disease15 (Figure 2, G). While the underlying mechanism of this finding is largely unknown, this phenomenon is attributed to the status of pseudohypoxia resulting in HIF-1a increase in the setting of VHL disease,15 since positivity for inhibin has not been observed in other clear cell NETs associated with MEN1 syndrome.22 Thus, positivity for inhibin is used to suggest the possibility of VHL disease underlying multifocal clear cell NETs.15 Regardless of the size or grade of NETs, pancreatic NETs are malignant neoplasms.21 Histologic signs of local aggressiveness, such as angioinvasion, perineural invasion, peritumoral adipose tissue infiltration, or poorly delineated tumors, were present in 60% of VHL pancreata with NETs. The identification of local aggressiveness features in these tumors is important as it can lead to life-threatening complications, such as severe upper gastrointestinal hemorrhage, duodenal stenosis, and/or cholangitis.8 266 Arch Pathol Lab Med—Vol 139, February 2015
Pheochromocytomas and Paragangliomas While pheochromocytomas are much more commonly reported in VHL disease, extra-adrenal paragangliomas can also be encountered in this setting. von Hippel-Lindau– related paragangliomas are usually parasympathetic and noncatecholamine releasing.25 In a series of 14 VHL-related pheochromocytomas, distinctive histopathologic features consisted of a thick vascular tumor capsule; presence of myxoid and hyalinized stroma; vessels intermixed with tumor cells; round, small to medium tumor cells with neuroendocrine nuclei and amphophilic and clear cytoplasm; and absence of cytoplasmic hyaline globules, nuclear atypia, or mitoses. In contrast to multiple endocrine neoplasia type 2 (MEN2)–related pheochromocytomas, adrenal medullary hyperplasia is not associated with VHLrelated pheochromocytomas.13,14 In a different series comprising 18 patients with VHL, electron microscopic analysis revealed distinct ultrastructural features of VHL-related pheochromocytomas, when compared to MEN2 syndrome. While MEN 2-related pheochromocytomas shared many of the characteristics of normal adrenal medullary chromaffin cells, those seen in VHL disease did not. They showed an increased amount of rough endoplasmic reticulum, with fewer secretory granules (mostly of the norepinephrine-containing type), and they were most frequently lined up for exocytosis along cell membranes, whereas in MEN2 syndrome they were evenly distributed throughout the cytoplasm.11 It has been speculated that this arrangement might result in a more continuous pattern of catecholamine release from VHLrelated tumors, compared with a more episodic pattern in MEN2 syndrome. The latter may therefore explain the increased frequency of paroxysmal signs and symptoms in MEN2 syndrome, when compared to VHL disease, for which many patients can be asymptomatic. A recent study26 has suggested that the presence of strong membranous immunohistochemical staining for carbonic anhydrase IX might be a distinctive feature of VHL-related pheochromocytomas; however, this might need further validation, since only 3 of the 100 tumors included in that study harbored VHL mutations. DIFFERENTIAL DIAGNOSIS VHL–related pancreatic NETs, especially those with clear cell changes, must be distinguished from metastatic lesions with clear cell morphology, such as renal cell carcinomas and pheochromocytomas/extra-adrenal paragangliomas, which are also characteristic of VHL. Acinar cell carcinoma, serous microcystic adenoma, and solid pseudopapillary pancreatic neoplasm are also differential diagnosis considerations.4 Serous microcystic adenomas can occur simultaneously in patients with pancreatic NETs and can display clear cells; however, these are usually glycogen-rich, while in VHL NETs, cytoplasmic clearing results from lipid and/or glycogen accumulation.6,15 While pancreatic NETs and pheochromocytomas/extra-adrenal paragangliomas express chromogranin A and synaptophysin, renal cell carcinomas remain negative for neuroendocrine differentiation marker. Moreover, clear cell renal cell carcinomas tend to have thin fibrovascular network rather than the broad collagen bands commonly seen in VHL-related NETs.4 Inhibin immunohistochemistry may also be an adjunctive in the differential diagnosis of clear cell pancreatic NET versus metastatic renal cell carcinoma, as it has shown positive results in the former VHL Disease—Cassol & Mete
and negative results in the latter.15,16 Inhibin-expressing clear cell NETs can also mimic clear cell adrenal cortical carcinoma; thus, positivity for steroidogenic factor–1 along with other cortical differentiation markers (Melan-A, calretinin, and synaptophysin) can be used in this distinction. Of note, clear cell pancreatic NETs can also occur, although less commonly, in patients with MEN1 syndrome22; therefore, the finding of a clear cell pancreatic NET should not prompt the pathologist to reflexively suggest the patient be examined for VHL, but should also bring MEN1 to consideration in the differential diagnosis. However, inhibin positivity in a patient with multifocal clear cell pancreatic NET suggests the possibility of VHL disease.15 Adrenal hemangioblastomas, although rare, are a differential diagnosis consideration for pheochromocytomas in the VHL setting, as they can have similar imaging findings and may uncommonly cause an increase in urinary catecholamines.27 One should also remember that NETs can sometimes be negative for keratins. Since patients with VHL can also get paragangliomas, which are typically negative for keratins, positivity for tyrosine hydroxylase, the rate-limiting enzyme in the synthesis of catecholamines, should be assessed to render a diagnosis of paraganglioma when dealing with a keratin-negative neuroendocrine neoplasm14 (Figure 2, H). LABORATORY FINDINGS AND ANCILLARY STUDIES Quantification of chromogranin A may be useful in confirming the diagnosis of a pancreatic NET and assessing for persistent, recurrent, or metastatic disease.28 Endoscopic ultrasonography is considered one of the most sensitive modalities to image pancreatic NETs. It not only allows visualization of lesions that are too small to be detected by other techniques but also provides the ability to perform biopsies and tattoo small lesions of interest to assist the surgical team at the time of operation, which is especially valuable if a laparoscopic approach is planned.28 Somatostatin receptor scintigraphy is another widespread technique to detect pancreatic NETs and their metastases; however, it seems to have a lower diagnostic accuracy for VHL-related pancreatic NETs (60%) than for sporadic ones (usually reported as .85%).8 This might be due to a less frequent and weaker expression of somatostatin receptor type 2A (SST2) in VHL-related tumors and a lack of correlation between SST2 immunohistochemical positivity and somatostatin receptor scintigraphy detection, as illustrated in a recent series of 29 VHL patients with pancreatic NETs, in which the expression of SST2 was weak (less than normal islets) in 7 of 15 tumors tested (47%), and the 8 remaining tumors were negative.8 Of note, there is a genotype-biochemical phenotype correlation in paragangliomas/pheochromocytomas. VHL– related paragangliomas/pheochromocytomas show increased levels of dopamine and norepinephrine.11,14 This might be due to a reduced expression of tyrosine hydroxylase and phenylethanolamine N-methyltransferase (enzyme that converts norepinephrine to epinephrine) in VHL-related pheochromocytomas.11 It has also been postulated to be one of the reasons why patients with VHL are less likely to present with hypertension (especially of the paroxysmal type) than patients with MEN2.11 Thus, measurement of plasma normetanephrine levels is reported to be the most sensitive test for detecting pheochromocyArch Pathol Lab Med—Vol 139, February 2015
toma in VHL disease, and in families at risk it is recommended that screening starts before age 16 years.1 Several imaging methods are currently available to localize paragangliomas arising in VHL disease; these include magnetic resonance imaging, computed tomography, (iodine)-methyl-benzyl-guanidine or octreotide scintigraphy, 18F-(fluoride)-DOPA-positron emission tomography, and 18F-dopamine and 18F-deoxyglucose scans.2 CURRENT TREATMENT AND PROGNOSIS The prognosis of VHL disease was once believed to be largely determined by outcome of the treatment of renal cell carcinomas, the most frequently metastasizing VHL-related tumor.3 However, with the advances in renal cell carcinoma therapy, including the use of nephron-sparing surgery and other nonsurgical techniques (eg, radiofrequency ablation), outcomes for renal cell carcinoma have improved and NETs have emerged as a significant source of malignant disease, with metastasis risks ranging from 11% to 17% in some series.5,8 When considering treatment strategies for VHLrelated pancreatic NETs, factors that have to be taken into consideration include how these tumors differ from sporadic NETs by their tendency to be multiple, asymptomatic, with overall indolent behavior. Therefore, noninterventional options might be desirable to reduce mortality and morbidity, such as potential loss of pancreatic function. Based on their observations of the natural behavior of VHLassociated NETs and the specific prognostic criteria identified for these tumors, Blansfield et al29 came up with suggestions for their optimal treatment. Tumors with no factors of adverse prognosis (namely, tumor size .3 cm, presence of exon 3 mutations, or doubling size time ,500 days) were considered as having low metastatic potential, and an acceptable management strategy would include performing a history with physical and imaging examinations every 2 to 3 years. For tumors with 1 of the abovementioned adverse prognostic factors, more frequent follow-up was suggested (every 6 to 12 months), while for tumors with 2 or 3 adverse prognostic factors, surgical intervention should be considered.5 Since VHL pancreatic NETs are frequently multiple, the use of intraoperative ultrasonography is recommended to assist in the detection of additional lesions at the time of surgery, as well as to assess their proximity to the pancreatic duct and feasibility of enucleation. In tumors lying close to the duct, a resection may be safer than enucleation, given that the risk of fistula is higher in this setting.5 Recent studies30 have also shown that decreased chromogranin A, decreased cytoplasmic chromogranin B, and increased cytoplasmic p53 expression are associated with aggressive behavior in VHL-associated pancreatic NETs, but these findings need validation in different cohorts of patients before they can be translated into clinical practice. Currently, there are no accepted interventional procedures for management of localized pancreatic NETs; however, interventional procedures have been developed for the treatment of regional metastases to the liver, including transarterial embolization, radiofrequency ablation, internal radiotherapy, and infusional chemotherapy.28 In patients with advanced disease, somatostatin analogues such as octreotide are recommended. These are most effective when disease can be imaged via somatostatin receptor scintigraphy.28 Historically, pancreatic NETs have been resistant to standard chemotherapy. Most recently, promising results VHL Disease—Cassol & Mete 267
have been achieved with the use of targeted agents such as sunitinib, everolimus, and bevacizumab.28 For VHL-associated pheochromocytomas, the treatment is surgery, preferably laparoscopic. In hypertensive patients, a- and sometimes b-adrenergic blockers may be required preoperatively to achieve normotension. Since VHL-associated pheochromocytomas tend to be bilateral and/or multiple, adrenal-sparing surgery, which preserves adrenal cortical function, should be attempted to prevent permanent glucocorticoid deficiency. Since no single histologic parameter is able to predict malignant behavior in paragangliomas and pheochromocytomas,14 lifelong follow-up is required owing to the risk of late recurrences in VHL disease; however, malignant disease is rare, occurring at a frequency of approximately 5% or lower.2 It is of note that according to the 2004 WHO classification of endocrine neoplasms, malignancy of pheochromocytomas and extra-adrenal paragangliomas is defined by the presence of metastases to sites where paraganglial tissue is not normally found.14 CONCLUSION Pancreatic NETs and pheochromocytomas/paragangliomas are important endocrine manifestations of VHL disease. They frequently display characteristic clinical, biochemical, and histopathologic features that, although not pathognomonic, can be helpful in suggesting VHL disease as the underlying etiology and distinguishing these tumors from sporadic cases. Recent improvements in treatment and outcome of renal cell carcinomas (the most frequent VHLassociated metastasizing tumors) have allowed pancreatic NETs to emerge as a significant source of metastatic disease, making the accurate recognition and classification of these neoplasms by the pathologist of utmost importance to determine prognosis, treatment, and follow-up strategies for affected patients. References 1. Maher ER, Neumann HP, Richard S. von Hippel-Lindau disease: a clinical and scientific review. Eur J Hum Genet. 2011;19(6):617–623. 2. Barontini M, Dahia PL. VHL disease. Best Pract Res Clin Endocrinol Metab. 2010;24(3):401–413. 3. Shuin T, Yamasaki I, Tamura K, Okuda H, Furihata M, Ashida S. Von Hippel-Lindau disease: molecular pathological basis, clinical criteria, genetic testing, clinical features of tumors and treatment. Jpn J Clin Oncol. 2006;36(6): 337–343. 4. Safo AO, Pambuccian SE. Pancreatic manifestations of von Hippel-Lindau disease. Arch Pathol Lab Med. 2010;134(7):1080–1083. 5. Charlesworth M, Verbeke CS, Falk GA, Walsh M, Smith AM, Morris-Stiff G. Pancreatic lesions in von Hippel-Lindau disease: a systematic review and metasynthesis of the literature. J Gastrointest Surg. 2012;16(7):1422–1428. 6. Lubensky IA, Pack S, Ault D, et al. Multiple neuroendocrine tumors of the pancreas in von Hippel-Lindau disease patients: histopathological and molecular genetic analysis. Am J Pathol. 1998;153(1):223–231. 7. Hammel PR, Vilgrain V, Terris B, et al. Pancreatic involvement in von Hippel-Lindau disease: the Groupe Francophone d’Etude de la Maladie de von Hippel-Lindau. Gastroenterology. 2000;119(4):1087–1095. 8. Corcos O, Couvelard A, Giraud S, et al. Endocrine pancreatic tumors in von Hippel-Lindau disease: clinical, histological, and genetic features. Pancreas. 2008;37(1):85–93.
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9. Libutti SK, Choyke PL, Alexander HR, et al. Clinical and genetic analysis of patients with pancreatic neuroendocrine tumors associated with von HippelLindau disease. Surgery. 2000;128(6):1022–1027. 10. Woodward ER, Maher ER. Von Hippel-Lindau disease and endocrine tumor susceptibility. Endocr Relat Cancer. 2006;13(2):415–425. 11. Eisenhofer G, Walther MM, Huynh TT, et al. Pheochromocytomas in von Hippel-Lindau syndrome and multiple endocrine neoplasia type 2 display distinct biochemical and clinical phenotypes. J Clin Endocrinol Metab. 2001; 86(5):1999–2008. 12. Srirangalingam U, Khoo B, Walker L, et al. Contrasting clinical manifestations of SDHB and VHL associated chromaffin tumors. Endocr Relat Cancer. 2009;16(2):515–525. 13. Koch CA, Mauro D, Walther MM, et al. Pheochromocytoma in von HippelLindau disease: distinct histopathologic phenotype compared to pheochromocytoma in multiple endocrine neoplasia type 2. Endocr Pathol. 2002;13(1):17– 27. 14. Mete O, Tischler A, de Krijger R, et al. Protocol for the examination of specimens from patients with pheochromocytomas and extra-adrenal paragangliomas. Arch Pathol Lab Med. 2014;138(2):182–188. 15. Gucer H, Szentgyorgi E, Ezzat S, Asa SL, Mete O. Inhibin-expressing clear cell neuroendocrine tumor of the ampulla: an unusual presentation of Von Hippel-Lindau Disease. Virchows Arch. 2013;463(4):593–597. 16. Sinkre PA, Murakata L, Rabin L, Hoang MP, Albores-Saavedra J. Clear cell carcinoid tumor of the gallbladder: another distinctive manifestation of von Hippel-Lindau disease. Am J Surg Pathol. 2001;25(10):1334–1339. 17. Mete O, Asa SL. Precursor lesions of endocrine system neoplasms. Pathology. 2013;45(3):316–330. 18. Fellows IW, Leach IH, Smith PG, Toghill PJ, Doran J. Carcinoid tumor of the common bile duct-a novel complication of von Hippel-Lindau syndrome. Gut. 1990;31(6):728–729. 19. Tudorancea A, Fran¸cois P, Trouillas J, et al. Von Hippel-Lindau disease and aggressive GH-PRL pituitary adenoma in a young boy. Ann Endocrinol (Paris). 2012;73(1):37–42. 20. Arao T, Okada Y, Tanikawa T, et al. A case of von Hippel-Lindau disease with bilateral pheochromocytoma, renal cell carcinoma, pelvic tumor, spinal hemangioblastoma and primary hyperparathyroidism. Endocr J. 2002;49(2):181– 188. 21. Bosman FT, Carneiro F, Hruban RH, Theise ND, eds. WHO Classification of Tumors of the Digestive System. 4th ed. Lyon, France: IARC Press; 2010. World Health Organization Classification of Tumours; vol 3. 22. Fryer E, Serra S, Chetty R. Lipid-rich (‘‘clear cell’’) neuroendocrine tumors of the pancreas in MEN I patients. Endocr Pathol. 2012;23(4):243–246. 23. Mylonis I, Sembongi H, Befani C, Liakos P, Siniossoglou S, Simos G. Hypoxia causes triglyceride accumulation by HIF-1-mediated stimulation of lipin 1 expression. J Cell Sci. 2012;125(14):3485–3493. 24. Pelletier J, Bellot G, Gounon P, Lacas-Gervais S, Pouyss´egur J, Mazure NM. Glycogen synthesis is induced in hypoxia by the hypoxia-inducible factor and promotes cancer cell survival. Front Oncol. 2012;2:18. 25. Gaal J, van Nederveen FH, Erlic Z, et al. Parasympathetic paragangliomas are part of the Von Hippel-Lindau syndrome. J Clin Endocrinol Metab. 2009; 94(11):4367–4371. 26. Pinato DJ, Ramachandran R, Toussi ST, et al. Immunohistochemical markers of the hypoxic response can identify malignancy in pheochromocytomas and paragangliomas and optimize the detection of tumors with VHL germline mutations. Br J Cancer. 2013;108(2):429–437. 27. Deb P, Pal S, Dutta V, Srivastava A, Bhargava A, Yadav KK. Adrenal hemangioblastoma presenting as pheochromocytoma: a rare manifestation of extraneural hemangioblastoma. Endocr Pathol. 2012;23(3):187–190. 28. Burns WR, Edil BH. Neuroendocrine pancreatic tumors: guidelines for management and update. Curr Treat Options Oncol. 2012;13(1):24–34. 29. Blansfield JA, Choyke L, Morita SY, et al. Clinical, genetic and radiographic analysis of 108 patients with von Hippel–Lindau disease (VHL) manifested by pancreatic neuroendocrine neoplasms (PNETs). Surgery. 2007;142(6):814–818. 30. Weisbrod AB, Zhang L, Jain M, Barak S, Quezado MM, Kebebew E. Altered PTEN, ATRX, CHGA, CHGB, and TP53 expression are associated with aggressive VHL-associated pancreatic neuroendocrine tumors. Horm Cancer. 2013;4(3): 165–175.
VHL Disease—Cassol & Mete
Endocrine Manifestations of von Hippel–Lindau Disease Clarissa Cassol, MD; Ozgur Mete, MD
von Hippel–Lindau (VHL) disease is an autosomal dominant disorder caused by heterozygous mutations in the VHL tumor suppressor gene that is characterized by the occurrence of multiple endocrine and nonendocrine lesions. This review focuses on the endocrine manifestations of VHL disease. Pancreatic neuroendocrine proliferations (ductuloinsular complexes, islet dysplasia, endocrine microadenoma, and neuroendocrine tumors), pheochromocytomas, and extra-adrenal paragangliomas are important endocrine manifestations of VHL disease. They frequently display characteristic clinical, biochemical, and histopathologic features that, although not pathognomonic, can be helpful in suggesting VHL disease as the underlying etiology and distinguishing these tumors from sporadic cases. Recent improvements in treatment and outcomes of renal cell carcinomas have allowed pancreatic neuroendocrine tumors to emerge as a significant source of metastatic disease, making the accurate recognition and classification of these neoplasms by the pathologist of utmost importance to determine prognosis, treatment, and follow-up strategies for affected patients. (Arch Pathol Lab Med. 2015;139:263–268; doi: 10.5858/ arpa.2013-0520-RS)
T
hemangiomas of the adrenal gland, liver, and lung; and a variety of solid tumors, including clear cell renal carcinomas, pheochromocytomas, paragangliomas, pancreatic neuroendocrine tumors (NETs), endolymphatic sac tumors, and papillary tumors of the broad ligament or epididymis (papillary cystadenoma).1 VHL lesions develop following the classic Knudson 2-hit hypothesis in which secondary inactivation of the nonmutated VHL allele leads to loss of pVHL function. This results in failure of polyubiquitination and proteasomal degradation of HIF, which is central for the pathogenesis of the disease. The resulting high levels of HIF create a state of pseudohypoxia leading to transcriptional activation of genes linked to erythropoiesis, angiogenesis, and cell metabolism. This condition will contribute to the development of highly vascularized tumors typical of VHL and the commonly observed erythrocytosis in affected patients.1 Most recently, HIF-independent pVHL functions have also been uncovered that may play a role in VHL tumorigenesis. Those include apoptosis regulation, cell senescence control, microtubule stabilization and maintenance of the primary cilium, and regulation of extracellular matrix formation and cell-cell adhesion.2 Corroborating the role of VHL protein loss in the development of VHL-related tumors is the fact that some sporadic renal cell carcinomas, hemangioblastomas, and pheochromocytomas also harbor VHL biallelic inactivation.3 In this review, we will focus on the endocrine manifestations of VHL disease.
Accepted for publication November 18, 2013. From the Department of Pathology, University Health Network, Toronto, Ontario, Canada, and the Department of Laboratory Medicine and Pathobiology, University of Toronto, Ontario, Canada. The authors have no relevant financial interest in the products or companies described in this article. Reprints: Ozgur Mete, MD, Department of Pathology, University Health Network, 200 Elizabeth St, 11th Floor, Toronto, ON M5G 2C4, Canada (e-mail: [email protected]).
DIAGNOSIS AND CLINICAL FEATURES The incidence of VHL disease is estimated to be at least 1 per 36 000 individuals.1 The penetrance is age dependent, but reaches approximately 95% by age 65 years.1 In patients with a positive family history, a clinical diagnosis of VHL disease can be made by the finding of a single VHLassociated tumor.1 Approximately 20% of cases result from de novo mutations and therefore do not have a positive family history.2 In these cases the presence of at least 2 VHL-associated tumors is required for the diagnosis.1 Whenever a clinical diagnosis of VHL disease is suspected, individuals should be referred for genetic screening for VHL gene mutation detection. In the past, up to 20% of patients with a clinical diagnosis were reported to have no VHL mutations on screening; however, current improvements in genetic diagnosis make it possible to detect mutations in virtually all cases.2 Genotype-phenotype correlations form the basis for the clinical classification of VHL disease. Type 1 disease does not include pheochromocytoma as one of its features and is generally caused by whole or partial gene deletion or nonsense mutation, while type 2 disease is characterized by
he von Hippel–Lindau (VHL) disease (MIM 193300) is an autosomal dominant disorder caused by heterozygous mutations in the VHL tumor suppressor gene (3p25.3). The VHL gene encodes a 232-amino-acid protein (pVHL), which is essential in the regulation of the hypoxia-inducible factor (HIF)–1 and HIF-2 affecting the upregulation of vascular endothelial growth factor (VEGF), platelet-derived growth factor beta (PDGFb), transforming growth factor alpha (TGFa), and erythropoietin substances. While heterozygous VHL mutations cause VHL disease, homozygous mutations result in familial erythrocytosis-2 (ECYT2; 263400) (http://omim.org; accessed November 9, 2013). VHL disease is characterized by the occurrence of multiple nonendocrine and endocrine lesions, including hemangioblastomas of the retina, cerebellum, or spinal cord; visceral cysts (especially of the kidney, pancreas, and liver);
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severe upper gastrointestinal hemorrhage, duodenal stenosis, and/or cholangitis.8 The mean age at which pancreatic NETs are diagnosed in patients with VHL disease is lower than in sporadic cases (35 versus 58 years),6,9 which is probably due to periodic screening in these patients and may contribute to the better prognosis observed for VHL-associated NETs when compared to sporadic ones.10 As previously mentioned, pheochromocytomas occur only in type 2 VHL disease, accounting for 10% of all cases.3 Similar to pancreatic NETs, pheochromocytomas in patients with VHL also tend to be diagnosed at a younger age (approximately 20 years) than in sporadic cases (mean age at diagnosis, 43.9 years).10 They are usually bilateral adrenal, multiple, or extra-adrenal2 and can be asymptomatic.11 Malignant disease is relatively rare, at about 5% or lower, and head and neck tumors are infrequent.2
Figure 1. Gross features of von Hippel-Lindau (VHL)–related pancreatic neuroendocrine tumors and pheochromocytomas/extra-adrenal paragangliomas. Pancreatic neuroendocrine tumors associated with VHL disease are often multiple and are located throughout the pancreas. Grossly, they are well-demarcated, variegated, and brown to yellow tan masses (star), most commonly in the background of cystic disease. A, Grossly, the presence of a thick vascular tumor capsule has been suggested to be a distinctive feature of VHL-related pheochromocytomas or extra-adrenal paragangliomas. B, Arrows indicate the presence of thick tumor capsule.
the occurrence of pheochromocytomas and is associated with missense mutations. Type 2 disease can be further subdivided in type 2A (low risk of renal cell carcinoma), type 2B (high risk of renal cell carcinoma), and type 2C (pheochromocytoma only).2 Pancreatic lesions are common in VHL disease and often present with benign cystic disease including microcystic or serous adenomas, which occur in up to 70% of patients with VHL.1 These lesions rarely prompt a VHL diagnosis and are most often discovered incidentally during abdominal imaging screening.4 Simple cysts and serous cystadenomas have uncommonly been associated with symptoms of abdominal mass or obstructive jaundice, while pancreatic NETs are usually clinically nonfunctioning5 and can rarely present with abdominal pain, nausea, or diarrhea.6 Possible complications of these lesions include compression of the main pancreatic duct, leading to pancreatitis,7 and compression or invasion of adjacent organs, which can result in 264 Arch Pathol Lab Med—Vol 139, February 2015
GROSS PATHOLOGY Pancreatic NETs associated with VHL disease are often multiple and are located throughout the pancreas.6 Grossly, they are well-demarcated, variegated, and red-brown to yellow tan masses, most commonly in the background of cystic disease (Figure 1, A).4,6 A fibrotic focus, defined as a scarlike fibrosclerotic area located within the tumor and containing a variable number of fibroblasts admixed with collagen fibers, was observed in 76% of pancreatic NETs in 1 series.8 This feature has been shown to be associated with a worse prognosis in several other carcinomas and has been postulated to represent a hypoxic phenomenon in advanced tumors.8 VHL–related pheochromocytomas can be bilateral in up to 60% of cases.12 Grossly, the presence of a thick vascular tumor capsule has been suggested to be a distinctive feature of VHL-related pheochromocytomas or extra-adrenal paragangliomas (Figure 1, B).13,14 In 2 series of VHL-related pheochromocytomas, mean tumor sizes were 3.25 and 3.7 cm.12,13 HISTOPATHOLOGY The common endocrine manifestations of VHL disease include neuroendocrine neoplasms arising from adrenal medulla (pheochromocytoma) and extra-adrenal paraganglia (paraganglioma) along with pancreatic NETs. VHL– related pancreatic NETs and paragangliomas/pheochromocytomas will be discussed in detail in this section. Other rare neuroendocrine tumors reported in patients with VHL include clear cell NETs in the ampulla and gallbladder,15,16 a clinically functioning duodenal D cell NET,17 a NET of the common bile duct,18 an aggressive growth hormone– prolactin-producing pituitary adenoma,19 and a parathyroid adenoma with primary hyperparathyroidism.20 Pancreatic Neuroendocrine Proliferations Among patients with VHL disease who undergo abdominal imaging, up to 77% have some pancreatic lesion detected,7 most commonly pancreatic cysts, of which 86% are multiple5 (Figure 2, A). Serous microcystic adenomas (also known as serous cystadenomas) have been identified in approximately 10% of patients and are also frequently multiple.4 A pancreatic neuroendocrine proliferation reaching a size of 0.5 cm is termed a neuroendocrine tumor (NET). Pancreatic NETs have been described in 11% to 17% of patients with VHL disease.8 Similar to multiple endocrine neoplasia type 1 (MEN1) syndrome, patients with VHL VHL Disease—Cassol & Mete
Figure 2. Histopathologic and immunohistochemical features of neuroendocrine proliferations associated with von Hippel–Lindau (VHL) disease. Pancreatic pathologic features in VHL usually take the form of benign cysts (A), and pancreatic neuroendocrine tumors are less common. Similar to multiple endocrine neoplasia type 1 syndrome, VHL disease can be associated with precursor lesions including ductuloinsular complexes, islet dysplasia, pancreatic microadenomas (A; asterisk), and peliosis (B) of the nontumorous islets. von Hippel-Lindau–related pancreatic neuroendocrine tumors (NETs) can have solid, trabecular, or glandular architecture with stromal fibrosis (C). Both pancreatic NETs and pheochromocytomas/extraadrenal paragangliomas characteristically contain clear cells or multivacuolated lipid-rich cells in varying proportions (C and D) that can sometimes mimic signet ring cell carcinoma (E). These neoplasms can express peptide hormones. Pancreatic polypeptide–expressing, VHL-related pancreatic NET is illustrated in this example (F). Positivity for inhibin is used to suggest the possibility of VHL disease underlying multifocal clear cell neuroendocrine tumors (G). Positivity for tyrosine hydroxylase should be assessed to render a diagnosis of paraganglioma when dealing with a keratin-negative neuroendocrine neoplasm (H) (hematoxylin-eosin, original magnifications 32.5 [A], 340 [B and E], and 320 [C and D]; Pancreatic polypeptide, inhibin, and tyrosine hydroxylase, original magnifications, 320[ F, G, and H]). Arch Pathol Lab Med—Vol 139, February 2015
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disease can be associated with precursor lesions including ductuloinsular complexes (nesidioblastosis), islet dysplasia (referring to normal-sized or slightly enlarged islets ,0.5 mm that contain neuroendocrine cells showing loss of the normal spatial and quantitative arrangement of the normal a, b, d, and PP cell types), pancreatic microadenomatosis (when islet dysplasia is between 0.5–5 mm, it is termed microadenoma; multiple microadenomas are termed microadenomatosis), and peliosis of the nontumorous islets17 (Figure 2, A and B). Similar to other pancreatic NETs, VHL-related pancreatic NETs should be classified according to the 2010 World Health Organization (WHO) classification, which uses a 3tier grading system: grade 1 NET: Ki-67 of 2% or less and/or mitotic activity less than 2 mitoses per 10 high-power fields (HPFs); grade 2 NET: Ki-67: 3% to 20% and/or mitotic activity equal to 2 to 20 mitoses per 10 HPFs; and grade 3 neuroendocrine carcinoma: Ki-67 index greater than 20% and/or mitotic activity greater than 20 mitoses per 10 HPFs.21 VHL–related pancreatic NETs can have solid, trabecular, or glandular architecture. Prominent stromal collagen bands have been observed6 (Figure 2, C). These tumors are hypervascular5 and characteristically contain clear cells or multivacuolated lipid-rich cells in varying proportion15,17 (Figure 2, C and D) along with nuclear features characteristic of NETs. Clear cells in these tumors frequently coexist with lipid-containing foamy cells, and it has been suggested they are actually an exaggerated form of foamy cytoplasm with coalescence of small lipid vacuoles and the formation of a large vacuole that occupies the entire cytoplasm, thus creating an empty space.22 This phenomenon is also attributed to the activation of HIF1-a, leading to a status of pseudohypoxia resulting in lipid and glycogen accumulation in tumor cells.15 It has been shown that HIF-mediated stimulation of lipin 1 expression causes triglyceride accumulation.23 Furthermore, glycogen synthesis is induced in hypoxia by HIF-1 and promotes tumor cell survival.24 This phenomenon can sometimes mimic a signet ring cell carcinoma15 (Figure 2, E). These neoplasms are positive for chromogranin A and synaptophysin by immunohistochemistry and can be focally positive for somatostatin, pancreatic polypeptide (Figure 2, F), vasoactive intestinal peptide, insulin, and/or glucagon.6 Interestingly, none have shown gastrin positivity,6 which is in contrast with MEN1-associated NETs, which are gastrin producing in up to 50% of cases.17 Interestingly, inhibin positivity has been reported in clear cell NETs associated with VHL disease15 (Figure 2, G). While the underlying mechanism of this finding is largely unknown, this phenomenon is attributed to the status of pseudohypoxia resulting in HIF-1a increase in the setting of VHL disease,15 since positivity for inhibin has not been observed in other clear cell NETs associated with MEN1 syndrome.22 Thus, positivity for inhibin is used to suggest the possibility of VHL disease underlying multifocal clear cell NETs.15 Regardless of the size or grade of NETs, pancreatic NETs are malignant neoplasms.21 Histologic signs of local aggressiveness, such as angioinvasion, perineural invasion, peritumoral adipose tissue infiltration, or poorly delineated tumors, were present in 60% of VHL pancreata with NETs. The identification of local aggressiveness features in these tumors is important as it can lead to life-threatening complications, such as severe upper gastrointestinal hemorrhage, duodenal stenosis, and/or cholangitis.8 266 Arch Pathol Lab Med—Vol 139, February 2015
Pheochromocytomas and Paragangliomas While pheochromocytomas are much more commonly reported in VHL disease, extra-adrenal paragangliomas can also be encountered in this setting. von Hippel-Lindau– related paragangliomas are usually parasympathetic and noncatecholamine releasing.25 In a series of 14 VHL-related pheochromocytomas, distinctive histopathologic features consisted of a thick vascular tumor capsule; presence of myxoid and hyalinized stroma; vessels intermixed with tumor cells; round, small to medium tumor cells with neuroendocrine nuclei and amphophilic and clear cytoplasm; and absence of cytoplasmic hyaline globules, nuclear atypia, or mitoses. In contrast to multiple endocrine neoplasia type 2 (MEN2)–related pheochromocytomas, adrenal medullary hyperplasia is not associated with VHLrelated pheochromocytomas.13,14 In a different series comprising 18 patients with VHL, electron microscopic analysis revealed distinct ultrastructural features of VHL-related pheochromocytomas, when compared to MEN2 syndrome. While MEN 2-related pheochromocytomas shared many of the characteristics of normal adrenal medullary chromaffin cells, those seen in VHL disease did not. They showed an increased amount of rough endoplasmic reticulum, with fewer secretory granules (mostly of the norepinephrine-containing type), and they were most frequently lined up for exocytosis along cell membranes, whereas in MEN2 syndrome they were evenly distributed throughout the cytoplasm.11 It has been speculated that this arrangement might result in a more continuous pattern of catecholamine release from VHLrelated tumors, compared with a more episodic pattern in MEN2 syndrome. The latter may therefore explain the increased frequency of paroxysmal signs and symptoms in MEN2 syndrome, when compared to VHL disease, for which many patients can be asymptomatic. A recent study26 has suggested that the presence of strong membranous immunohistochemical staining for carbonic anhydrase IX might be a distinctive feature of VHL-related pheochromocytomas; however, this might need further validation, since only 3 of the 100 tumors included in that study harbored VHL mutations. DIFFERENTIAL DIAGNOSIS VHL–related pancreatic NETs, especially those with clear cell changes, must be distinguished from metastatic lesions with clear cell morphology, such as renal cell carcinomas and pheochromocytomas/extra-adrenal paragangliomas, which are also characteristic of VHL. Acinar cell carcinoma, serous microcystic adenoma, and solid pseudopapillary pancreatic neoplasm are also differential diagnosis considerations.4 Serous microcystic adenomas can occur simultaneously in patients with pancreatic NETs and can display clear cells; however, these are usually glycogen-rich, while in VHL NETs, cytoplasmic clearing results from lipid and/or glycogen accumulation.6,15 While pancreatic NETs and pheochromocytomas/extra-adrenal paragangliomas express chromogranin A and synaptophysin, renal cell carcinomas remain negative for neuroendocrine differentiation marker. Moreover, clear cell renal cell carcinomas tend to have thin fibrovascular network rather than the broad collagen bands commonly seen in VHL-related NETs.4 Inhibin immunohistochemistry may also be an adjunctive in the differential diagnosis of clear cell pancreatic NET versus metastatic renal cell carcinoma, as it has shown positive results in the former VHL Disease—Cassol & Mete
and negative results in the latter.15,16 Inhibin-expressing clear cell NETs can also mimic clear cell adrenal cortical carcinoma; thus, positivity for steroidogenic factor–1 along with other cortical differentiation markers (Melan-A, calretinin, and synaptophysin) can be used in this distinction. Of note, clear cell pancreatic NETs can also occur, although less commonly, in patients with MEN1 syndrome22; therefore, the finding of a clear cell pancreatic NET should not prompt the pathologist to reflexively suggest the patient be examined for VHL, but should also bring MEN1 to consideration in the differential diagnosis. However, inhibin positivity in a patient with multifocal clear cell pancreatic NET suggests the possibility of VHL disease.15 Adrenal hemangioblastomas, although rare, are a differential diagnosis consideration for pheochromocytomas in the VHL setting, as they can have similar imaging findings and may uncommonly cause an increase in urinary catecholamines.27 One should also remember that NETs can sometimes be negative for keratins. Since patients with VHL can also get paragangliomas, which are typically negative for keratins, positivity for tyrosine hydroxylase, the rate-limiting enzyme in the synthesis of catecholamines, should be assessed to render a diagnosis of paraganglioma when dealing with a keratin-negative neuroendocrine neoplasm14 (Figure 2, H). LABORATORY FINDINGS AND ANCILLARY STUDIES Quantification of chromogranin A may be useful in confirming the diagnosis of a pancreatic NET and assessing for persistent, recurrent, or metastatic disease.28 Endoscopic ultrasonography is considered one of the most sensitive modalities to image pancreatic NETs. It not only allows visualization of lesions that are too small to be detected by other techniques but also provides the ability to perform biopsies and tattoo small lesions of interest to assist the surgical team at the time of operation, which is especially valuable if a laparoscopic approach is planned.28 Somatostatin receptor scintigraphy is another widespread technique to detect pancreatic NETs and their metastases; however, it seems to have a lower diagnostic accuracy for VHL-related pancreatic NETs (60%) than for sporadic ones (usually reported as .85%).8 This might be due to a less frequent and weaker expression of somatostatin receptor type 2A (SST2) in VHL-related tumors and a lack of correlation between SST2 immunohistochemical positivity and somatostatin receptor scintigraphy detection, as illustrated in a recent series of 29 VHL patients with pancreatic NETs, in which the expression of SST2 was weak (less than normal islets) in 7 of 15 tumors tested (47%), and the 8 remaining tumors were negative.8 Of note, there is a genotype-biochemical phenotype correlation in paragangliomas/pheochromocytomas. VHL– related paragangliomas/pheochromocytomas show increased levels of dopamine and norepinephrine.11,14 This might be due to a reduced expression of tyrosine hydroxylase and phenylethanolamine N-methyltransferase (enzyme that converts norepinephrine to epinephrine) in VHL-related pheochromocytomas.11 It has also been postulated to be one of the reasons why patients with VHL are less likely to present with hypertension (especially of the paroxysmal type) than patients with MEN2.11 Thus, measurement of plasma normetanephrine levels is reported to be the most sensitive test for detecting pheochromocyArch Pathol Lab Med—Vol 139, February 2015
toma in VHL disease, and in families at risk it is recommended that screening starts before age 16 years.1 Several imaging methods are currently available to localize paragangliomas arising in VHL disease; these include magnetic resonance imaging, computed tomography, (iodine)-methyl-benzyl-guanidine or octreotide scintigraphy, 18F-(fluoride)-DOPA-positron emission tomography, and 18F-dopamine and 18F-deoxyglucose scans.2 CURRENT TREATMENT AND PROGNOSIS The prognosis of VHL disease was once believed to be largely determined by outcome of the treatment of renal cell carcinomas, the most frequently metastasizing VHL-related tumor.3 However, with the advances in renal cell carcinoma therapy, including the use of nephron-sparing surgery and other nonsurgical techniques (eg, radiofrequency ablation), outcomes for renal cell carcinoma have improved and NETs have emerged as a significant source of malignant disease, with metastasis risks ranging from 11% to 17% in some series.5,8 When considering treatment strategies for VHLrelated pancreatic NETs, factors that have to be taken into consideration include how these tumors differ from sporadic NETs by their tendency to be multiple, asymptomatic, with overall indolent behavior. Therefore, noninterventional options might be desirable to reduce mortality and morbidity, such as potential loss of pancreatic function. Based on their observations of the natural behavior of VHLassociated NETs and the specific prognostic criteria identified for these tumors, Blansfield et al29 came up with suggestions for their optimal treatment. Tumors with no factors of adverse prognosis (namely, tumor size .3 cm, presence of exon 3 mutations, or doubling size time ,500 days) were considered as having low metastatic potential, and an acceptable management strategy would include performing a history with physical and imaging examinations every 2 to 3 years. For tumors with 1 of the abovementioned adverse prognostic factors, more frequent follow-up was suggested (every 6 to 12 months), while for tumors with 2 or 3 adverse prognostic factors, surgical intervention should be considered.5 Since VHL pancreatic NETs are frequently multiple, the use of intraoperative ultrasonography is recommended to assist in the detection of additional lesions at the time of surgery, as well as to assess their proximity to the pancreatic duct and feasibility of enucleation. In tumors lying close to the duct, a resection may be safer than enucleation, given that the risk of fistula is higher in this setting.5 Recent studies30 have also shown that decreased chromogranin A, decreased cytoplasmic chromogranin B, and increased cytoplasmic p53 expression are associated with aggressive behavior in VHL-associated pancreatic NETs, but these findings need validation in different cohorts of patients before they can be translated into clinical practice. Currently, there are no accepted interventional procedures for management of localized pancreatic NETs; however, interventional procedures have been developed for the treatment of regional metastases to the liver, including transarterial embolization, radiofrequency ablation, internal radiotherapy, and infusional chemotherapy.28 In patients with advanced disease, somatostatin analogues such as octreotide are recommended. These are most effective when disease can be imaged via somatostatin receptor scintigraphy.28 Historically, pancreatic NETs have been resistant to standard chemotherapy. Most recently, promising results VHL Disease—Cassol & Mete 267
have been achieved with the use of targeted agents such as sunitinib, everolimus, and bevacizumab.28 For VHL-associated pheochromocytomas, the treatment is surgery, preferably laparoscopic. In hypertensive patients, a- and sometimes b-adrenergic blockers may be required preoperatively to achieve normotension. Since VHL-associated pheochromocytomas tend to be bilateral and/or multiple, adrenal-sparing surgery, which preserves adrenal cortical function, should be attempted to prevent permanent glucocorticoid deficiency. Since no single histologic parameter is able to predict malignant behavior in paragangliomas and pheochromocytomas,14 lifelong follow-up is required owing to the risk of late recurrences in VHL disease; however, malignant disease is rare, occurring at a frequency of approximately 5% or lower.2 It is of note that according to the 2004 WHO classification of endocrine neoplasms, malignancy of pheochromocytomas and extra-adrenal paragangliomas is defined by the presence of metastases to sites where paraganglial tissue is not normally found.14 CONCLUSION Pancreatic NETs and pheochromocytomas/paragangliomas are important endocrine manifestations of VHL disease. They frequently display characteristic clinical, biochemical, and histopathologic features that, although not pathognomonic, can be helpful in suggesting VHL disease as the underlying etiology and distinguishing these tumors from sporadic cases. Recent improvements in treatment and outcome of renal cell carcinomas (the most frequent VHLassociated metastasizing tumors) have allowed pancreatic NETs to emerge as a significant source of metastatic disease, making the accurate recognition and classification of these neoplasms by the pathologist of utmost importance to determine prognosis, treatment, and follow-up strategies for affected patients. References 1. Maher ER, Neumann HP, Richard S. von Hippel-Lindau disease: a clinical and scientific review. Eur J Hum Genet. 2011;19(6):617–623. 2. Barontini M, Dahia PL. VHL disease. Best Pract Res Clin Endocrinol Metab. 2010;24(3):401–413. 3. Shuin T, Yamasaki I, Tamura K, Okuda H, Furihata M, Ashida S. Von Hippel-Lindau disease: molecular pathological basis, clinical criteria, genetic testing, clinical features of tumors and treatment. Jpn J Clin Oncol. 2006;36(6): 337–343. 4. Safo AO, Pambuccian SE. Pancreatic manifestations of von Hippel-Lindau disease. Arch Pathol Lab Med. 2010;134(7):1080–1083. 5. Charlesworth M, Verbeke CS, Falk GA, Walsh M, Smith AM, Morris-Stiff G. Pancreatic lesions in von Hippel-Lindau disease: a systematic review and metasynthesis of the literature. J Gastrointest Surg. 2012;16(7):1422–1428. 6. Lubensky IA, Pack S, Ault D, et al. Multiple neuroendocrine tumors of the pancreas in von Hippel-Lindau disease patients: histopathological and molecular genetic analysis. Am J Pathol. 1998;153(1):223–231. 7. Hammel PR, Vilgrain V, Terris B, et al. Pancreatic involvement in von Hippel-Lindau disease: the Groupe Francophone d’Etude de la Maladie de von Hippel-Lindau. Gastroenterology. 2000;119(4):1087–1095. 8. Corcos O, Couvelard A, Giraud S, et al. Endocrine pancreatic tumors in von Hippel-Lindau disease: clinical, histological, and genetic features. Pancreas. 2008;37(1):85–93.
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9. Libutti SK, Choyke PL, Alexander HR, et al. Clinical and genetic analysis of patients with pancreatic neuroendocrine tumors associated with von HippelLindau disease. Surgery. 2000;128(6):1022–1027. 10. Woodward ER, Maher ER. Von Hippel-Lindau disease and endocrine tumor susceptibility. Endocr Relat Cancer. 2006;13(2):415–425. 11. Eisenhofer G, Walther MM, Huynh TT, et al. Pheochromocytomas in von Hippel-Lindau syndrome and multiple endocrine neoplasia type 2 display distinct biochemical and clinical phenotypes. J Clin Endocrinol Metab. 2001; 86(5):1999–2008. 12. Srirangalingam U, Khoo B, Walker L, et al. Contrasting clinical manifestations of SDHB and VHL associated chromaffin tumors. Endocr Relat Cancer. 2009;16(2):515–525. 13. Koch CA, Mauro D, Walther MM, et al. Pheochromocytoma in von HippelLindau disease: distinct histopathologic phenotype compared to pheochromocytoma in multiple endocrine neoplasia type 2. Endocr Pathol. 2002;13(1):17– 27. 14. Mete O, Tischler A, de Krijger R, et al. Protocol for the examination of specimens from patients with pheochromocytomas and extra-adrenal paragangliomas. Arch Pathol Lab Med. 2014;138(2):182–188. 15. Gucer H, Szentgyorgi E, Ezzat S, Asa SL, Mete O. Inhibin-expressing clear cell neuroendocrine tumor of the ampulla: an unusual presentation of Von Hippel-Lindau Disease. Virchows Arch. 2013;463(4):593–597. 16. Sinkre PA, Murakata L, Rabin L, Hoang MP, Albores-Saavedra J. Clear cell carcinoid tumor of the gallbladder: another distinctive manifestation of von Hippel-Lindau disease. Am J Surg Pathol. 2001;25(10):1334–1339. 17. Mete O, Asa SL. Precursor lesions of endocrine system neoplasms. Pathology. 2013;45(3):316–330. 18. Fellows IW, Leach IH, Smith PG, Toghill PJ, Doran J. Carcinoid tumor of the common bile duct-a novel complication of von Hippel-Lindau syndrome. Gut. 1990;31(6):728–729. 19. Tudorancea A, Fran¸cois P, Trouillas J, et al. Von Hippel-Lindau disease and aggressive GH-PRL pituitary adenoma in a young boy. Ann Endocrinol (Paris). 2012;73(1):37–42. 20. Arao T, Okada Y, Tanikawa T, et al. A case of von Hippel-Lindau disease with bilateral pheochromocytoma, renal cell carcinoma, pelvic tumor, spinal hemangioblastoma and primary hyperparathyroidism. Endocr J. 2002;49(2):181– 188. 21. Bosman FT, Carneiro F, Hruban RH, Theise ND, eds. WHO Classification of Tumors of the Digestive System. 4th ed. Lyon, France: IARC Press; 2010. World Health Organization Classification of Tumours; vol 3. 22. Fryer E, Serra S, Chetty R. Lipid-rich (‘‘clear cell’’) neuroendocrine tumors of the pancreas in MEN I patients. Endocr Pathol. 2012;23(4):243–246. 23. Mylonis I, Sembongi H, Befani C, Liakos P, Siniossoglou S, Simos G. Hypoxia causes triglyceride accumulation by HIF-1-mediated stimulation of lipin 1 expression. J Cell Sci. 2012;125(14):3485–3493. 24. Pelletier J, Bellot G, Gounon P, Lacas-Gervais S, Pouyss´egur J, Mazure NM. Glycogen synthesis is induced in hypoxia by the hypoxia-inducible factor and promotes cancer cell survival. Front Oncol. 2012;2:18. 25. Gaal J, van Nederveen FH, Erlic Z, et al. Parasympathetic paragangliomas are part of the Von Hippel-Lindau syndrome. J Clin Endocrinol Metab. 2009; 94(11):4367–4371. 26. Pinato DJ, Ramachandran R, Toussi ST, et al. Immunohistochemical markers of the hypoxic response can identify malignancy in pheochromocytomas and paragangliomas and optimize the detection of tumors with VHL germline mutations. Br J Cancer. 2013;108(2):429–437. 27. Deb P, Pal S, Dutta V, Srivastava A, Bhargava A, Yadav KK. Adrenal hemangioblastoma presenting as pheochromocytoma: a rare manifestation of extraneural hemangioblastoma. Endocr Pathol. 2012;23(3):187–190. 28. Burns WR, Edil BH. Neuroendocrine pancreatic tumors: guidelines for management and update. Curr Treat Options Oncol. 2012;13(1):24–34. 29. Blansfield JA, Choyke L, Morita SY, et al. Clinical, genetic and radiographic analysis of 108 patients with von Hippel–Lindau disease (VHL) manifested by pancreatic neuroendocrine neoplasms (PNETs). Surgery. 2007;142(6):814–818. 30. Weisbrod AB, Zhang L, Jain M, Barak S, Quezado MM, Kebebew E. Altered PTEN, ATRX, CHGA, CHGB, and TP53 expression are associated with aggressive VHL-associated pancreatic neuroendocrine tumors. Horm Cancer. 2013;4(3): 165–175.
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