Tumor Biol. (2014) 35:11655–11658 DOI 10.1007/s13277-014-2455-2
RESEARCH ARTICLE
Primary epidural hemangiopericytoma in the sacrum: a rare case and literature review Jie Liu & Lei Cao & Lin Liu & Shifang Guo & Huiping Tai & Zhixing Chen
Received: 22 September 2013 / Accepted: 13 November 2013 / Published online: 20 August 2014 # International Society of Oncology and BioMarkers (ISOBM) 2014
Abstract Hemangiopericytoma (HPC) is an uncommon highly vascular neoplasm that originated from Zimmerman’s pericytes which surrounds the endothelial tissue. Primary epidural HPC of the sacrum is extremely rare. We reported an unusual case of primary epidural malignant HPC of the sacrum that invaded vertebral bone and caused rectum compression in a 57-year-old male for the first time. The patient presented progressive low back pain and ribbon-like stool over 3 months. The surgical intervention involved sacrectomy and en bloc resection of the tumor. We described the clinical, radiological, and histological features of this tumor and reviewed the literature.
system or skin. The pericytes are spindle cells surrounding the capillaries and postcapillary venules, and the cell provides mechanical support to enable the capillaries to have contractile power [3]. Primary HPC occurs in both sexes with equal frequency and mainly in adults but rarely in children [3]. They occur most often in the fifth and sixth decades of life in the soft tissue form and the fourth and fifth decades in the osseous form, with a slight predominance of osseous HPC among males [4].
Keywords Hemangiopericytoma . Sacrectomy . Sacral vertebrae
A 57-year-old male presented with progressive sacrodynia and ribbon-like stool over 3 months, without either sensory abnormalities or muscle weakness in his lower extremities. Urinary incontinence, hypotonia, and increased deep tendon reflexes were not found. Plain X-ray of pelvis showed absorption of the right sacrum (Fig. 1a, b). Computed tomography (CT) scan of this region revealed an infiltrating mass involving the vertebral body of sacrum, with compression of the sacral nerves and rectum (Fig. 1c). Magnetic resonance images (MRI) showed an infiltrating mass involved the vertebral body from S2 to S5. The tumor was hyperintense in relation to the surrounding muscle in the T1- and T2-weighted images (Fig. 1d, e). The angiography of the patient showed “spider-shaped” appearance in the arterial phase and dense well-demarcated oval tumor staging in the venous phase (Fig. 2a, b). The patient underwent a preoperative endovascular embolization due to the pronounced tendency for hemorrhage throughout the surgical procedures. The patient was placed in a prone position. The incision was made from the spinous process of L5 to the tip of the coccyx. The lateral dissection was carried out to expose the sciatic notch. The sacrotuberous and sacrospinous ligaments
Introduction Hemangiopericytoma (HPC) is a type of soft tissue sarcoma that originates in the pericytes in the walls of capillaries. When inside the nervous system, although not strictly a meningioma, it is a tumor with a special aggressive behavior. This neoplasm accounts for less than 1 % of all vascular tumor and 5 % of all sarcomatous tumors [1]. HPC originates from the cell that surrounds endothelial tissue, which is known as Zimmerman’s pericytes [2]. Therefore, HPC can occur wherever endothelial tissue exists and develops primarily in the musculoskeletal J. Liu : L. Liu (*) : S. Guo : H. Tai : Z. Chen Orthopaedics Department, Gansu Province People’s Hospital, Lanzhou, Gansu 730000, China e-mail: [email protected] L. Cao Gansu Provincial Maternity and Child-care Hospital, Lanzhou, Gansu 730050, China
Case description
11656
Tumor Biol. (2014) 35:11655–11658
a
b
c
d
e
f
g
Fig. 1 Radiological images of the patient. a The anteroposterior view of the pelvis of the right sacrum (plain X-ray image). b Lateral view of the pelvis of the right sacrum (plain X-ray image). c CT scan of the sacrum showing the neoplasm. d Sagittal T2-weighted MRI showing the tumor
and compression of the rectum and sacral nerve. e Axial T2-weighted MRI showing the neoplasm. f Postoperative sagittal T1-weighted MRI. g Postoperative sagittal T2-weighted MRI
were identified and cut caudally. Anterior dissection was then begun over the coccyx. The levator muscles were then cut to expose the retroperitoneal area. Dissection was carried out bluntly on the anterior aspect of the sacrum up
to the anterior aspect of the tumor. If the nerve identified was not involved with the tumor, it was then preserved. Then, the sacrococcyx and the tumor were cut completely (Fig. 1f, g).
Fig. 2 The angiography and optical microscopy examination with hematoxylin-eosin staining. a The angiography of the patient showed “spider-shaped” appearance in the arterial phase. b The angiography of the phase after endovascular embolization. c Tumor cells were arranged in sheets and fascicles with intervening staghorn-shaped blood vessels (20×10). d Tumor cells had round to oval hyperchromatic nuclei, and at the cell border, there were modest amounts of indistinct eosinophilic cytoplasm (40×10)
a
b
c
d
Tumor Biol. (2014) 35:11655–11658
A paravertebral mass measuring about 8×8×9 cm3 with a smooth rubbery surface was seen. The cut surface showed brown to red area with multiple hemorrhagic foci. Multiple fragments of bony tissue were also identified. Optical microscopy examination of hematoxylin-eosin (HE)-stained tissue sections showed tumor cells that were arranged in sheets and fascicles with intervening staghornshaped blood vessels. The individual tumor cell had round to oval hyperchromatic nucleus, and at the cell border, there were modest amounts of indistinct eosinophilic cytoplasm. Multiple area of necrosis was also seen. There were frequent mitotic figures and increased cellularity. Immunohistochemical study showed positive vimentin staining and CD34, but negative reaction to factor VIII, S-100 protein, actin, CKP, EMA, and desmin (Fig. 2c, d).
Discussion HPC is regarded as a rare tumor that can occur wherever the endothelial tissue is found. It was first reported by Stout and Murray [5]. The most common sites for HPC are the lower extremities, followed by the retroperitoneum, and the head and neck regions [6]. But others [7, 8] reported that the most common sites were the head and the neck. Primary HPC of the spinal column is extremely rare [9]. The clinical presentation of HPC varies depending on the tumor size and localization. Pain and swelling are the most common complaints. Our patient had tenderness and pain. The skin overlying the mass does not have any discoloration or redness to indicate vascular origin. It is because the surrounding capillaries are emptied of blood by compression of the massive numbers of pericytes surrounding the tumor [10]. Most cases of HPC are present for several months to years prior to removal [7]. A rare case of HPC may cause constipation or hypoglycemia [7, 11], but with the tumor removal, the symptoms are abated. The etiology of this disease is uncertain, and no strong clinical data exist to indicate a convincing link to specific causative agent. Some reports indicated a relationship between HPC and occupational vinyl chloride exposure, as well as herbicidal exposure [12, 13]. These tumors can be locally aggressive, recur locally, and even metastasize. The lung and bone are the most common sites for metastasis [6]. An unusual feature of the HPC is the prolonged period, up to 16 years, between the diagnosis of the primary HPC and the metastases to the spine [14]. Radiographically, whether by MRI, CT, or plain X-ray film, HPC is not specific and usually appears as wellencapsulated 122 soft tissue mass [9, 15, 16]. An angiogram may show evidence of rapid circulation, indicated by a richly vascular mass with dilation of the arteries and a diffuse capillary blush or opacification in the arterial phase, a dense
11657
uniform tumor, and dilation of the draining vessels in the vicinity of the tumor in the venous stage [7]. The natural history of HPC correlates well with cellularity, mitotic activity, anaplasia, necrosis, and hemorrhage. Four or more mitoses per high-power microscopy field, necrotic foci, and increased cellularity are suggestive of malignancy and poor prognosis [3]. Adequate surgical resection, when feasible, is the first choice of treatment in all cases of HPC. Preoperative endovascular embolization is recommended because of the pronounced tendency to hemorrhage throughout biopsy and surgical procedures. Embolization also can be done mechanically or through the use of chemicals that cause blood vessels to close. If cytotoxic agents are used, this method is referred as chemoembolization [17]. HPC, like some sarcomas, is considered to be relatively resistant to radiotherapy, thus requiring high doses. Combs et al. [18] reported that high-precision radiotherapy is an effective and safe treatment modality for patients with HPC of the spine and achieves highly acceptable tumor control while sparing the normal tissue. HPC is an uncommon tumor, especially in the spine. Diagnosis often is delayed if patients are asymptomatic or present with a number of vague complaints [19]. Although HPC is rare in the spine, it should be kept in mind in the differential diagnosis of a spinal tumor. The differential diagnosis and the respective diagnostic features include solitary fibrous tumor (strong uniform CD34 and BCL-2 as well as scattered factor VIIIa immunoreactivity), metastatic carcinoma (keratin and epithelial membrane antigen immunoreactivity), mesenchymal chondrosarcoma (islands of hyaline cartilage), and perhaps hemangioma (tubular architecture and strong C31, CD34, and factor B immunoreactivity) [20–23].
Conflicts of interest None
References 1. Jiang LD, Tao C, He AY. Prognostic significance of p53 expression in malignant bone tumors: a meta-analysis. Tumor Biol. 2013;34(2): 1037–43. 2. Marcus RB, Post JC, Mancuso AA. Pediatric tumors of the head and neck. In: Million RR, Cassisi NJ, editors. Management of head and neck cancer: a multidisciplinary approach. 2nd ed. Philadelphia: Lippincott; 1994. p. 811–39. 3. Perez CA, Chao KS. Unusual nonepithelial tumors of the head and neck. In: Perez CA, Brady LW, editors. Principles and practice of radiation oncology. 3rd ed. Philadelphia: Lippincott-Raven; 1998. p. 1095–134. 4. Hama R, Watanabe Y, Shinada K, Yamada Y, Ogata Y, Yoshida Y, et al. Characterization of DNA hypermethylation in two cases of peritoneal mesothelioma. Tumor Biol. 2012;33(6):2031–40. 5. Stout AP, Murray MR. Hemangiopericytoma: a vascular tumor featuring Zimmerman’s pericytes. Ann Surg. 1942;116(1):26–33.
11658 6. Espat NJ, Lewis JJ, Leung D, Woodruff JM, Antonescu CR, Shia J, et al. Conventional hemangiopericytoma: modern analysis of outcome. Cancer. 2002;95(8):1746–51. 7. Weiss SW, Goldblum JR. Enzinger and Weiss’s soft tissue tumors. 4th ed. St. Louis: Mosby; 2001. 8. Starks A, Guo LF, Abraham JA. Resection of soft tissue tumors extending through the obturator ring. Orthopedics. 2013;36(9): e1220–4. 9. Mohammadianpanah M, Torabinejad S, Bagheri MH, Omidvari S, Mosalaei A, Ahmadloo N. Primary epidural malignant hemangiopericytoma of thoracic spinal column causing cord compression: case report. São Paulo Méd. 2004;122(5):220–2. 10. Gudrun R. Haemangiopericytoma in otolaryngology. J Laryngol Otol. 1979;93(3):477–94. 11. Pavelic K, Spaventi S, Gluncic V, Matejcic A, Pavicic D, Karapandza N. The expression and role of insulin-like growth factor II in malignant hemangiopericytomas. J Mol Med. 1999;77(12):865–9. 12. Hozo I, Miric D, Bojic L, Giunio L, Lusic I, Culic V. Liver angiosarcoma and hemangiopericytoma after occupational exposure to vinyl chloride monomer. Environ Health Perspect. 2000;108(8): 793–5. 13. de Assis Caldas Pereira F, Gurgel CAS, Ramos EAG, Vidal MTA, Pinheiro ALB, Jurisic V, et al. Distribution of mast cells in benign odontogenic tumors. Tumor Biol. 2012;33(2):455–61. 14. Brass SD, Guiot MC, Albrecht S, et al. Metastatic hemangiopericytoma presenting as an epidural spinal cord lesion. Can J Neurol Sci. 2004;31(4):550–3.
Tumor Biol. (2014) 35:11655–11658 15. Lian YW, Yao MS, Hsieh SC, Lao WT, Fang CL, Chan WP. MRI of hemangiopericytoma in the sacrum. Skelet Radiol. 2004;33(5):485–7. 16. Tayoro K, Cottier J, Jan M, Herbreteau D. Imaging of meningeal hemangiopericytomas. J Radiol. 2002;83(4):459–65. 17. Hogle WP. Malignant hemangiopericytoma: a clinical overview and case study. Clin J Oncol Nurs. 2003;7(1):57–62. 18. Combs SE, Thilman C, Debus J, Schulz-Ertner D. Precision radiotherapy for hemangiopericytomas of the central nervous system. Cancer. 2005;104(11):2457–65. 19. Morandi U, Stefani A, DeSantis M, Paci M, Lodi R. Preoperative embolization in surgical treatment of mediastinal hemangiopericytoma. Ann Thorac Surg. 2000;69(3):937–9. 20. Perry A, Scheithauer BW, Nascimento AG. The immunophenotypic spectrum of meningeal hemangiopericytoma: a comparison with fibrous meningioma and solitary fibrous tumor of meninges. Am J Surg Pathol. 1997;21(11):1354–60. 21. Carneiro SS, Scheithauer BW, Nascimmento AG. Solitary fibrous tumor of meninges: a lesion distinct from the fibrous meningioma. A clinicopathologic and immunohistochemical study. Am J Clin Pathol. 1996;106(2):217–24. 22. Molnar P, Nemes Z. Hemangiopericytoma of cerebello-pontine angle. Diagnostic pitfalls and the diagnostic value of the subunit A of factor VIII as a tumor marker. Clin Neuropathol. 1995;14(1):19–24. 23. Yan W, Xiao J, Liu T, Huang W, Yang X, Wu Z, et al. The effects of Hsp90 expression alteration on spinal metastases of breast carcinoma. Tumor Biol. 2013;34(3):1391–7.
RESEARCH ARTICLE
Primary epidural hemangiopericytoma in the sacrum: a rare case and literature review Jie Liu & Lei Cao & Lin Liu & Shifang Guo & Huiping Tai & Zhixing Chen
Received: 22 September 2013 / Accepted: 13 November 2013 / Published online: 20 August 2014 # International Society of Oncology and BioMarkers (ISOBM) 2014
Abstract Hemangiopericytoma (HPC) is an uncommon highly vascular neoplasm that originated from Zimmerman’s pericytes which surrounds the endothelial tissue. Primary epidural HPC of the sacrum is extremely rare. We reported an unusual case of primary epidural malignant HPC of the sacrum that invaded vertebral bone and caused rectum compression in a 57-year-old male for the first time. The patient presented progressive low back pain and ribbon-like stool over 3 months. The surgical intervention involved sacrectomy and en bloc resection of the tumor. We described the clinical, radiological, and histological features of this tumor and reviewed the literature.
system or skin. The pericytes are spindle cells surrounding the capillaries and postcapillary venules, and the cell provides mechanical support to enable the capillaries to have contractile power [3]. Primary HPC occurs in both sexes with equal frequency and mainly in adults but rarely in children [3]. They occur most often in the fifth and sixth decades of life in the soft tissue form and the fourth and fifth decades in the osseous form, with a slight predominance of osseous HPC among males [4].
Keywords Hemangiopericytoma . Sacrectomy . Sacral vertebrae
A 57-year-old male presented with progressive sacrodynia and ribbon-like stool over 3 months, without either sensory abnormalities or muscle weakness in his lower extremities. Urinary incontinence, hypotonia, and increased deep tendon reflexes were not found. Plain X-ray of pelvis showed absorption of the right sacrum (Fig. 1a, b). Computed tomography (CT) scan of this region revealed an infiltrating mass involving the vertebral body of sacrum, with compression of the sacral nerves and rectum (Fig. 1c). Magnetic resonance images (MRI) showed an infiltrating mass involved the vertebral body from S2 to S5. The tumor was hyperintense in relation to the surrounding muscle in the T1- and T2-weighted images (Fig. 1d, e). The angiography of the patient showed “spider-shaped” appearance in the arterial phase and dense well-demarcated oval tumor staging in the venous phase (Fig. 2a, b). The patient underwent a preoperative endovascular embolization due to the pronounced tendency for hemorrhage throughout the surgical procedures. The patient was placed in a prone position. The incision was made from the spinous process of L5 to the tip of the coccyx. The lateral dissection was carried out to expose the sciatic notch. The sacrotuberous and sacrospinous ligaments
Introduction Hemangiopericytoma (HPC) is a type of soft tissue sarcoma that originates in the pericytes in the walls of capillaries. When inside the nervous system, although not strictly a meningioma, it is a tumor with a special aggressive behavior. This neoplasm accounts for less than 1 % of all vascular tumor and 5 % of all sarcomatous tumors [1]. HPC originates from the cell that surrounds endothelial tissue, which is known as Zimmerman’s pericytes [2]. Therefore, HPC can occur wherever endothelial tissue exists and develops primarily in the musculoskeletal J. Liu : L. Liu (*) : S. Guo : H. Tai : Z. Chen Orthopaedics Department, Gansu Province People’s Hospital, Lanzhou, Gansu 730000, China e-mail: [email protected] L. Cao Gansu Provincial Maternity and Child-care Hospital, Lanzhou, Gansu 730050, China
Case description
11656
Tumor Biol. (2014) 35:11655–11658
a
b
c
d
e
f
g
Fig. 1 Radiological images of the patient. a The anteroposterior view of the pelvis of the right sacrum (plain X-ray image). b Lateral view of the pelvis of the right sacrum (plain X-ray image). c CT scan of the sacrum showing the neoplasm. d Sagittal T2-weighted MRI showing the tumor
and compression of the rectum and sacral nerve. e Axial T2-weighted MRI showing the neoplasm. f Postoperative sagittal T1-weighted MRI. g Postoperative sagittal T2-weighted MRI
were identified and cut caudally. Anterior dissection was then begun over the coccyx. The levator muscles were then cut to expose the retroperitoneal area. Dissection was carried out bluntly on the anterior aspect of the sacrum up
to the anterior aspect of the tumor. If the nerve identified was not involved with the tumor, it was then preserved. Then, the sacrococcyx and the tumor were cut completely (Fig. 1f, g).
Fig. 2 The angiography and optical microscopy examination with hematoxylin-eosin staining. a The angiography of the patient showed “spider-shaped” appearance in the arterial phase. b The angiography of the phase after endovascular embolization. c Tumor cells were arranged in sheets and fascicles with intervening staghorn-shaped blood vessels (20×10). d Tumor cells had round to oval hyperchromatic nuclei, and at the cell border, there were modest amounts of indistinct eosinophilic cytoplasm (40×10)
a
b
c
d
Tumor Biol. (2014) 35:11655–11658
A paravertebral mass measuring about 8×8×9 cm3 with a smooth rubbery surface was seen. The cut surface showed brown to red area with multiple hemorrhagic foci. Multiple fragments of bony tissue were also identified. Optical microscopy examination of hematoxylin-eosin (HE)-stained tissue sections showed tumor cells that were arranged in sheets and fascicles with intervening staghornshaped blood vessels. The individual tumor cell had round to oval hyperchromatic nucleus, and at the cell border, there were modest amounts of indistinct eosinophilic cytoplasm. Multiple area of necrosis was also seen. There were frequent mitotic figures and increased cellularity. Immunohistochemical study showed positive vimentin staining and CD34, but negative reaction to factor VIII, S-100 protein, actin, CKP, EMA, and desmin (Fig. 2c, d).
Discussion HPC is regarded as a rare tumor that can occur wherever the endothelial tissue is found. It was first reported by Stout and Murray [5]. The most common sites for HPC are the lower extremities, followed by the retroperitoneum, and the head and neck regions [6]. But others [7, 8] reported that the most common sites were the head and the neck. Primary HPC of the spinal column is extremely rare [9]. The clinical presentation of HPC varies depending on the tumor size and localization. Pain and swelling are the most common complaints. Our patient had tenderness and pain. The skin overlying the mass does not have any discoloration or redness to indicate vascular origin. It is because the surrounding capillaries are emptied of blood by compression of the massive numbers of pericytes surrounding the tumor [10]. Most cases of HPC are present for several months to years prior to removal [7]. A rare case of HPC may cause constipation or hypoglycemia [7, 11], but with the tumor removal, the symptoms are abated. The etiology of this disease is uncertain, and no strong clinical data exist to indicate a convincing link to specific causative agent. Some reports indicated a relationship between HPC and occupational vinyl chloride exposure, as well as herbicidal exposure [12, 13]. These tumors can be locally aggressive, recur locally, and even metastasize. The lung and bone are the most common sites for metastasis [6]. An unusual feature of the HPC is the prolonged period, up to 16 years, between the diagnosis of the primary HPC and the metastases to the spine [14]. Radiographically, whether by MRI, CT, or plain X-ray film, HPC is not specific and usually appears as wellencapsulated 122 soft tissue mass [9, 15, 16]. An angiogram may show evidence of rapid circulation, indicated by a richly vascular mass with dilation of the arteries and a diffuse capillary blush or opacification in the arterial phase, a dense
11657
uniform tumor, and dilation of the draining vessels in the vicinity of the tumor in the venous stage [7]. The natural history of HPC correlates well with cellularity, mitotic activity, anaplasia, necrosis, and hemorrhage. Four or more mitoses per high-power microscopy field, necrotic foci, and increased cellularity are suggestive of malignancy and poor prognosis [3]. Adequate surgical resection, when feasible, is the first choice of treatment in all cases of HPC. Preoperative endovascular embolization is recommended because of the pronounced tendency to hemorrhage throughout biopsy and surgical procedures. Embolization also can be done mechanically or through the use of chemicals that cause blood vessels to close. If cytotoxic agents are used, this method is referred as chemoembolization [17]. HPC, like some sarcomas, is considered to be relatively resistant to radiotherapy, thus requiring high doses. Combs et al. [18] reported that high-precision radiotherapy is an effective and safe treatment modality for patients with HPC of the spine and achieves highly acceptable tumor control while sparing the normal tissue. HPC is an uncommon tumor, especially in the spine. Diagnosis often is delayed if patients are asymptomatic or present with a number of vague complaints [19]. Although HPC is rare in the spine, it should be kept in mind in the differential diagnosis of a spinal tumor. The differential diagnosis and the respective diagnostic features include solitary fibrous tumor (strong uniform CD34 and BCL-2 as well as scattered factor VIIIa immunoreactivity), metastatic carcinoma (keratin and epithelial membrane antigen immunoreactivity), mesenchymal chondrosarcoma (islands of hyaline cartilage), and perhaps hemangioma (tubular architecture and strong C31, CD34, and factor B immunoreactivity) [20–23].
Conflicts of interest None
References 1. Jiang LD, Tao C, He AY. Prognostic significance of p53 expression in malignant bone tumors: a meta-analysis. Tumor Biol. 2013;34(2): 1037–43. 2. Marcus RB, Post JC, Mancuso AA. Pediatric tumors of the head and neck. In: Million RR, Cassisi NJ, editors. Management of head and neck cancer: a multidisciplinary approach. 2nd ed. Philadelphia: Lippincott; 1994. p. 811–39. 3. Perez CA, Chao KS. Unusual nonepithelial tumors of the head and neck. In: Perez CA, Brady LW, editors. Principles and practice of radiation oncology. 3rd ed. Philadelphia: Lippincott-Raven; 1998. p. 1095–134. 4. Hama R, Watanabe Y, Shinada K, Yamada Y, Ogata Y, Yoshida Y, et al. Characterization of DNA hypermethylation in two cases of peritoneal mesothelioma. Tumor Biol. 2012;33(6):2031–40. 5. Stout AP, Murray MR. Hemangiopericytoma: a vascular tumor featuring Zimmerman’s pericytes. Ann Surg. 1942;116(1):26–33.
11658 6. Espat NJ, Lewis JJ, Leung D, Woodruff JM, Antonescu CR, Shia J, et al. Conventional hemangiopericytoma: modern analysis of outcome. Cancer. 2002;95(8):1746–51. 7. Weiss SW, Goldblum JR. Enzinger and Weiss’s soft tissue tumors. 4th ed. St. Louis: Mosby; 2001. 8. Starks A, Guo LF, Abraham JA. Resection of soft tissue tumors extending through the obturator ring. Orthopedics. 2013;36(9): e1220–4. 9. Mohammadianpanah M, Torabinejad S, Bagheri MH, Omidvari S, Mosalaei A, Ahmadloo N. Primary epidural malignant hemangiopericytoma of thoracic spinal column causing cord compression: case report. São Paulo Méd. 2004;122(5):220–2. 10. Gudrun R. Haemangiopericytoma in otolaryngology. J Laryngol Otol. 1979;93(3):477–94. 11. Pavelic K, Spaventi S, Gluncic V, Matejcic A, Pavicic D, Karapandza N. The expression and role of insulin-like growth factor II in malignant hemangiopericytomas. J Mol Med. 1999;77(12):865–9. 12. Hozo I, Miric D, Bojic L, Giunio L, Lusic I, Culic V. Liver angiosarcoma and hemangiopericytoma after occupational exposure to vinyl chloride monomer. Environ Health Perspect. 2000;108(8): 793–5. 13. de Assis Caldas Pereira F, Gurgel CAS, Ramos EAG, Vidal MTA, Pinheiro ALB, Jurisic V, et al. Distribution of mast cells in benign odontogenic tumors. Tumor Biol. 2012;33(2):455–61. 14. Brass SD, Guiot MC, Albrecht S, et al. Metastatic hemangiopericytoma presenting as an epidural spinal cord lesion. Can J Neurol Sci. 2004;31(4):550–3.
Tumor Biol. (2014) 35:11655–11658 15. Lian YW, Yao MS, Hsieh SC, Lao WT, Fang CL, Chan WP. MRI of hemangiopericytoma in the sacrum. Skelet Radiol. 2004;33(5):485–7. 16. Tayoro K, Cottier J, Jan M, Herbreteau D. Imaging of meningeal hemangiopericytomas. J Radiol. 2002;83(4):459–65. 17. Hogle WP. Malignant hemangiopericytoma: a clinical overview and case study. Clin J Oncol Nurs. 2003;7(1):57–62. 18. Combs SE, Thilman C, Debus J, Schulz-Ertner D. Precision radiotherapy for hemangiopericytomas of the central nervous system. Cancer. 2005;104(11):2457–65. 19. Morandi U, Stefani A, DeSantis M, Paci M, Lodi R. Preoperative embolization in surgical treatment of mediastinal hemangiopericytoma. Ann Thorac Surg. 2000;69(3):937–9. 20. Perry A, Scheithauer BW, Nascimento AG. The immunophenotypic spectrum of meningeal hemangiopericytoma: a comparison with fibrous meningioma and solitary fibrous tumor of meninges. Am J Surg Pathol. 1997;21(11):1354–60. 21. Carneiro SS, Scheithauer BW, Nascimmento AG. Solitary fibrous tumor of meninges: a lesion distinct from the fibrous meningioma. A clinicopathologic and immunohistochemical study. Am J Clin Pathol. 1996;106(2):217–24. 22. Molnar P, Nemes Z. Hemangiopericytoma of cerebello-pontine angle. Diagnostic pitfalls and the diagnostic value of the subunit A of factor VIII as a tumor marker. Clin Neuropathol. 1995;14(1):19–24. 23. Yan W, Xiao J, Liu T, Huang W, Yang X, Wu Z, et al. The effects of Hsp90 expression alteration on spinal metastases of breast carcinoma. Tumor Biol. 2013;34(3):1391–7.
