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Neuropathology 2015; 35, 44–49
doi:10.1111/neup.12140
Cas e Rep o r t
Adenocarcinoma arising from intracranial recurrent mature teratoma and featuring mutated KRAS and wild-type BRAF genes Eun Soo Kim,1 Mi Jung Kwon,2 Joon Ho Song,3 Dong Hoon Kim2 and Hye-Rim Park2 Departments of 1Radiology, 2Pathology and 3Neurosurgery, Hallym University Sacred Heart Hospital, Hallym University College of Medicine, Anyang, Republic of Korea
Malignant transformation or recurrence of intracranial mature teratoma is an extremely rare occurrence, compared to the usual ovarian counterpart. Previously, yolk sac tumor elements have been considered to be selective progenitors of enteric-type adenocarcinoma arising from intracranial germ cell tumors. However, the present case demonstrates the occurrence of enteric-type adenocarcinoma in recurrent intracranial mature cystic teratoma 12 years after gross total removal, a case of which has not previously been documented in the literature. The 11.5-cm long, dura mater-based tumor on the right fronto-temporal lobe displaced the brain; however, the patient had no neurologic symptoms or discomfort other than pus-like discharge on the scalp. Microscopic examinations revealed a small focus of adenocarcinoma and dysplastic colonic mucosa in the mature cystic teratoma. No immature elements were seen. The cystic wall was almost denuded and showed an exuberant xanthogranulomatous reaction with foreign-body type giant cells engulfing keratin materials and cholesterol clefts, suggesting that chronic inflammation due to repeated cyst wall rupture and the previous resection may contribute to malignant transformation. The adenocarcinoma showed strong immunohistochemical expression of CK20 and p53, but CK7 in patches. The molecular profile of the adenocarcinoma showed a mutation in KRAS and wild-type BRAF, which might be associated with malignant transformation of intracranial mature teratomas. In conclusion, the intracranial mature
Correspondence: Mi Jung Kwon, MD, PhD, Department of Pathology, Hallym University Sacred Heart Hospital, Hallym University College of Medicine, 896, Pyeongchon-dong, Dongan-gu, Anyang, Gyeonggi-do 431-070, Republic of Korea. Email: mulank@ hanmail.net Received 8 April 2014; revised 13 May 2014 and accepted 14 May 2014; published online 11 July 2014.
© 2014 Japanese Society of Neuropathology
teratomas should require long-term follow-up, and clinicians, radiologists and pathologists should be aware of the potential for malignant progression of recurrent intracranial mature cystic teratoma despite gross total resection and no neurologic symptoms. Key words: adenocarcinoma, dura mater, immunohistochemistry, mature teratoma, recurrence.
INTRODUCTION Intracranial mature teratomas are rare extra-neuraxial germ cell tumors, characterized by the presence of highly differentiated adult-type tissues that arise from three germ cell layers.1 Comprising 0.5% of intracranial tumors, intracranial mature teratomas occur most often at the midline of the brain.1 In particular, the pathogenesis and clinical significance of dura-based mature teratomas outside the typical location are unrevealed. Malignant transformation or recurrence of an intracranial mature teratoma is an extremely rare event.1 Enteric-type adenocarcinoma arising from an intracranial mature teratoma is rare, with only one previously reported case.2 However, the adenocarcinoma previously described occurred in mixed germ cell tumors that were composed of yolk sac tumor, immature teratoma, and mature teratoma and not in a pure mature teratoma.2 Because of the co-existence of yolk sac tumors and adenocarcinoma arising from intracranial germ cell tumors, yolk sac tumor elements have been considered to be selective progenitors of enteric-type adenocarcinoma.1,2 The present case is characterized by the first report of the development of enteric-type adenocarcinoma in pure intracranial mature teratoma harboring mutated KRAS and wild-type BRAF genes. These molecular alterations may imply important roles in the malignant transformation of intracranial mature teratoma. In addition, the present case is unique in the recurrent huge mature cystic
Carcinoma in recurrent dural mature teratoma
45
Fig. 1 Sagittal (A) and coronal (B) MRI revealed a large, cylindrical, encapsulated fluid-filled cystic mass that measures approximately 11.5 × 2.5 × 3.0 cm and occupies a previous craniectomy site (white arrowhead) in the right frontal lobe. The mass extends into the right retro-maxillary area, through the greater wing of the right sphenoid bone. Adjacent pachymeningeal enhancement and thickening are observed (white arrows, A–D). Thick or nodular enhancements of the cystic mass were noted at the right intra-orbit (yellow arrow; D), pterygopalatine fossa (yellow arrow; E), infratemporal fossa, masticator space and posterolateral wall of the right maxillary sinus (yellow arrows; F) and were accompanied by bone erosion and perilesional soft tissue invasion.
teratoma that underwent malignant transformation at a tumor removal site 12 years after gross total removal. Herein, we present an exceptional case of adenocarcinoma from recurrent mature cystic teratoma developed in the extra-axial frontal dura growing to a huge mass without clinical awareness.
CLINICAL SUMMARY A 54-year-old Korean man presented with an oozing mass in the right frontal scalp area that had been enlarged and aggravated for 2 weeks. Twelve years previously, he had a 7-cm mature cystic teratoma removed from the same area but did not have follow-up evaluations after the surgery. Physical examination of the right frontal scalp area revealed a firm and fixed mass of approximately 3 cm in diameter; however, no neurological deficits were observed. At the site of the previous craniectomy, MRI showed a large, cylindrical, encapsulated, cystic mass with fluid that measured approximately 11.5 × 2.5 × 3.0 cm. The large mass extended into the right retro-maxillary area, through the greater wing of the right sphenoid bone (Fig. 1A–F). The mass showed diffuse thick enhancement at the peripheral wall and nodular enhancing lesions at the inner and outer portions of the wall. The mass appeared to arise from the dura mater and to encroach on the surrounding bone and soft tissue. The right fronto-temporal lobe of the brain was mildly compressed by the mass (Fig. 1A,D). Thick or nodular enhancement of the cystic mass was observed at the scalp and the dura of the previous craniectomy site in the right frontal lobe, as well as at the right intra-orbit, © 2014 Japanese Society of Neuropathology
pterygopalatine fossa, infratemporal fossa, masticator space, and posterolateral wall of the right maxillary sinus. Perilesional bony erosion, accompanied by surrounding soft tissue invasion, was observed. The adjacent pachymeningeal enhancement and thickening were suggestive of reactive change or pachymeningitis. No abnormal leptomeningeal enhancement and no focal lesion at brain parenchyma were observed by MRI. The patient underwent a gross total resection of the cystic mass. Intraoperative inspection revealed that the mass was adhered to the outer dura and retromaxillary fat pad. The mass was encapsulated and was partially golden-yellow, with a firm consistency. When the mass was opened, pus-like fluid was observed. The overlying skull bone showed hyperostosis with an irregular surface.
METHODS The tumor specimen was fixed in 10% buffered formalin, embedded in paraffin, and cut into 4 μm-thick sections. The sections were stained with HE, and immunohistochemistry was performed using the Discovery XT automated staining system (Ventana Medical Systems, Tucson, AZ, USA), according to the manufacturer’s protocol. The following primary antibodies, and dilutions, were used in immunoperoxidase reactions: anti-CK20 (1:50, Dako, Glostrup, Denmark), anti-CK7 (1:300, Dako), anti-Ki-67 (1:250, clone MIB-1, Dako) and anti-p53 (1:500, clone DO-7, Novocastra, Newcastle, UK). For molecular analysis, the cancerous area was manually microdissected under
46 a light microscope. Genomic DNA was extracted from sections using the QIAamp DNA Mini Kit (QIAGEN, Hilden, Germany). Mutational analyses for KRAS (codon 12 and 13) and BRAF (V600E) genes were performed using real-time quantitative PCR with peptide nucleic acid (PNA)-mediated clamping, using the PNAClampTM KRAS and BRAF Mutation Detection kits (PANAGENE, Daejeon, Korea), according to the manufacturer’s instructions, as previously described.3 Briefly, PNA probes and DNA primers are used together in the clamping reaction. The PNA probe, which has a sequence complementary to wild-type DNA, suppresses the amplification of wild-type target by competitively inhibiting primer binding to wildtype DNA. This results in a preferential amplification of mutant sequences. Positive signals were detected using the fluorescent dye. PCR efficiency was determined by measuring the threshold cycle (Ct) value. Ct values were obtained for the control and mutation assays by observing the amplification plots. Delta Ct (ΔCt) value was calculated as follows, ensuring that the sample and standard Ct values are from the tested sample and clamping control sample. [Standard Ct]-[Sample Ct] = ΔCt. The
ES Kim et al. cut-off ΔCt was defined as 2 for the KRAS and BRAF mutation.
PATHOLOGICAL FINDINGS Macroscopically, the cystic mass was unilocular, with an inner surface that showed grayish irregular fragile nodular lesions. Upon serial sectioning of the cystic mass, a yellowtan cut surface with calcified foci was revealed (Fig. 2A). Microscopically, a mature cystic teratoma with tissues arising from all three germ cell layers, including squamous epithelium, sebaceous and sweat glands, and adipose tissue, was observed (Fig. 2B). Ciliated respiratory type epithelium and salivary-type seromucinous glands were observed (Fig. 2C). Scattered bundles of smooth muscles (Fig. 2D) mixed with mature adipose tissue and bone formation were also observed. In addition, floating colonic mucosa with goblet cells was observed (Fig. 2E). No immature elements were seen. The majority of the cystic lining was denuded, and the fibrotic wall showed a xanthogranulomatous reaction, with foreign-body type giant cells engulfing keratin materials and cholesterol clefts (Fig. 2F).
Fig. 2 (A) The cut surfaces of the cystic mass show a thickened fibrotic wall that contains a grayish-yellow nodular lesion at the inner surface. (B) Squamous epithelium, sebaceous and sweat glands, and adipose tissue are observed at a 40 × magnification. (C) Ciliated respiratory type epithelium and salivary-type seromucinous glands are observed at a 200 × magnification. (D) Scattered bundles of smooth muscles and sweat glands are noted in the fibrous cystic wall (200 × magnification). (E) We noted floating colonic mucosa with goblet cells at a 400 × magnification. (F) The majority of the fibrotic wall shows a xanthogranulomatous reaction, with foreign body-type giant cells engulfing keratin materials and cholesterol clefts (200 × magnification). Scale bars = 250 μm (B) and 50 μm (C–F).
© 2014 Japanese Society of Neuropathology
Carcinoma in recurrent dural mature teratoma
47
Fig. 3 (A) A 0.8 × 0.7 cm cancerous focus (white arrow) is observed in the whitish gray nodular lesion. (B) The tumor infiltrates the cystic wall but does not extend beyond the cystic wall (40 × magnification). (C) The tumor displays well-formed tubular structures and clusters of fused or cribriform glands (100 × magnification). (D) The tumor cells show irregular enlarged nuclei, with prominent nucleoli and coarse chromatin, and the presence of atypical mitosis (400 × magnification). (E) Foci of low-grade dysplastic cells with hyperchromatic and stratified nuclei are observed, which show 7% of Ki-67 labeling index (F) and 100% of p53 expression (G) (400 × magnification). The adenocarcinoma stains diffusely positive for CK20 (H, 200 × magnification) and stains positive for CK7 in patches (I, 100 × magnification). The adenocarcinoma stains positive for Ki-67 (J) and shows strong, diffuse staining for p53 (K) (200 × magnification). (L) Real-time quantitative PCR analysis reveals a mutation of codon 12 of KRAS. Scale bars = 500 μm (B), 100 μm (C, I), and 50 μm (D–H, J–K). , Non PNA; , KRAS #12; , KRAS #13.
The whitish-gray nodular lesion showed a cancerous focus (0.8 × 0.7 cm) that displayed well-formed tubular structures and clusters of fused or cribriform glands infiltrating the cystic wall (Fig. 3A), which did not extend beyond the cystic wall (Fig. 3B). The tumor cells showed irregular enlarged nuclei, with prominent nucleoli and coarse chromatin, and atypical mitosis (Fig. 3C–D). Foci of mildly atypical elongated cells with hyperchromatic and stratified nuclei were observed in the adjacent area (Fig. 3E). Using immunohistochemistry, approximately 7% of those mildly atypical cells showed Ki-67 labeling index (Fig. 3F) and 100% of them showed p53 expression (Fig. 3G), which were favoring low-grade dysplastic cells. The adenocarcinoma stained diffusely positive for CK20 (Fig. 3H) and stained positive for CK7 in patches (Fig. 3I), suggesting enteric differentiation. Approximately 100% of cancer cells stained positive for Ki-67 protein (Fig. 3J) and approximately 100% of the cancer cells stained positive for p53 protein (Fig. 3K). Using real-time quantitative PCR, with PNA-mediated clamping, a mutation in codon 12 in KRAS gene (Fig. 3L) and wild-type BRAF gene were detected in the adenocarcinoma. © 2014 Japanese Society of Neuropathology
Histologic review of the initial specimen slides 12 years ago did not reveal any immature or malignant components within the mature teratoma. Upon these findings, a diagnosis of adenocarcinoma developing in the recurrent intracranial mature cystic teratoma was made and the molecular alterations were identified.
DISCUSSION An intracranial mature teratoma with malignant component is likely to be a borderline malignancy, while an intracranial pure mature teratoma is benign.4 The present case represents an initially histologically proven intracranial mature teratoma may relapse into malignant transformation. The tumor was a huge, cylindrical, encapsulated, cystic mass that originated from the dura covering the right frontotemporal lobe of the previous surgery site and extending into the right retro-maxillary area, compressing the brain. However, the patient showed no neurologic deficits or signs of meningitis, possibly as a result of the chronic incubation period and the slow-growing nature of the tumor.5 The time interval between initial surgery and
48 recurrence was 12 years, which is a long time for recurrence and malignant transformation. Adenocarcinoma may be derived from pre-existing intestinal epithelium within the teratoma; however, the mechanism of malignant transformation of the pre-existing epithelium is unknown. In our case, the cystic wall showed the denuded cystic lining and an exuberant xanthogranulomatous reaction with foreign body-type giant cells engulfing keratin materials and cholesterol clefts, suggesting that chronic inflammatory reaction due to repeated cyst wall rupture and the previous resection may result in dysplasia and contribute to malignant transformation.6,7 Histologically, the presence of dysplasia on the adenocarcinoma background may indicate that the cancerous focus might progress through a dysplasia-carcinoma sequence.8,9 In the present case, p53 immunoreactivity was diffuse in the dysplasia and the adenocarcinoma. Interestingly, in the presented case, we observed malignant transformation in recurrent dura mater-based teratoma that harbored a genetic alteration. The identified KRAS mutation has previously been reported in intestinal-type adenocarcinoma arising in ovarian mature teratoma.8 To the best of our knowledge, this is the first report of the identification of wild-type BRAF and a mutation in KRAS in intestinal-type adenocarcinoma originating in intracranial mature teratoma. KRAS and BRAF mutations are observed in approximately 30–54% and 10–18%, of colorectal adenocarcinomas, respectively.3,9,10 The mutation in KRAS may play an important role in the malignant transformation of mature teratoma, simulating the molecular events that underlie the carcinogenesis of colorectal carcinoma.8,9 In the presented case, the KRAS mutation and p53 dysregulation may be involved in the carcinogenesis events of the intracranial mature teratoma. Dura mater-based mature teratomas are rarely observed, although they are large tumors measuring up to 8 cm in length.5,11–14 The present tumor measured 11.5 cm at its longest, as the dura-based location provided the space to grow. The origin and pathogenesis of intracranial germ cell tumors are controversial. Zhao et al.11 have speculated that the dura mater may be the origin of extra-axial mature teratomas, whereas Sano4 has explained the development of germ cell tumors in the CNS by the “misinvolvementmisenfoldment” hypothesis during embryogenesis. The abnormal migration of embryonic cells into the dura mater may be responsible for the occurrence of dura-based mature teratomas and residual embryonic cells may be related to recurrence.11 In summary, the enteric-type adenocarcinoma arising in recurrent intracranial mature teratoma had a KRAS mutation and wild-type BRAF and showed p53 overexpression, which might be associated with malignant transformation of intracranial mature teratomas. The pre-
ES Kim et al. sent case suggests that intracranial mature teratomas should require long-term follow-up and clinicians, radiologists and pathologists should be aware of the potential for malignant progression of recurrent intracranial mature cystic teratoma despite gross total resection and no neurologic symptoms.
REFERENCES 1. Rosenblum MK, Nakazato Y, Matsutani M. CNS germ cell tumours. In: Louis DN, Ohgaki H, Wiestler OD, Cavenee WK, eds. WHO Classification of Tumours of the Central Nervous System, 4th edn. Lyon: International Agency for Research on Cancer (IARC), 2007; 198–204. 2. Freilich RJ, Thompson SJ, Walker RW, Rosenblum MK. Adenocarcinomatous transformation of intracranial germ cell tumors. Am J Surg Pathol 1995; 19: 537– 544. 3. Kwon MJ, Lee SE, Kang SY, Choi YL. Frequency of KRAS, BRAF, and PIK3CA mutations in advanced colorectal cancers: comparison of peptide nucleic acidmediated PCR clamping and direct sequencing in formalin-fixed, paraffin-embedded tissue. Pathol Res Pract 2011; 207: 762–768. 4. Sano K. So-called intracranial germ cell tumours: are they really of germ cell origin? Br J Neurosurg 1995; 9: 391–401. 5. Bonde V, Goel A, Goel NK. Giant interdural teratoma of the cavernous sinus. J Clin Neurosci 2008; 15: 1414– 1416. 6. Bjornsson J, Scheithauer BW, Okazaki H, Leech RW. Intracranial germ cell tumors: pathobiological and immunohistochemical aspects of 70 cases. J Neuropathol Exp Neurol 1985; 44: 32–46. 7. Pagni F, Brenna A, Leone BE, Vergani F, Isimbaldi G. Malignant epidermoid cyst of the pineal region with lumbar metastasis. Neuropathology 2007; 27: 566– 569. 8. Hershkovitz D, Vlodavsky E, Simon E, Ben-Izhak O. KRAS mutation positive mucinous adenocarcinoma originating in mature ovarian teratoma: case report and review of literature. Pathol Int 2013; 63: 611–614. 9. Leslie A, Carey FA, Pratt NR, Steele RJ. The colorectal adenoma-carcinoma sequence. Br J Surg 2002; 89: 845–860. 10. De Roock W, Claes B, Bernasconi D et al. Effects of KRAS, BRAF, NRAS, and PIK3CA mutations on the efficacy of cetuximab plus chemotherapy in chemotherapy-refractory metastatic colorectal cancer: a retrospective consortium analysis. Lancet Oncol 2010; 11: 753–762. © 2014 Japanese Society of Neuropathology
Carcinoma in recurrent dural mature teratoma 11. Zhao J, Wang H, Yu J, Zhong Y, Ge P. Cerebral falx mature teratoma with rare imaging in an adult. Int J Med Sci 2012; 9: 269–273. 12. Tobias S, Valarezo J, Meir K, Umansky F. Giant cavernous sinus teratoma: a clinical example of a rare entity: case report. Neurosurgery 2001; 48: 1367–1370; discussion 70–1.
© 2014 Japanese Society of Neuropathology
49 13. Muzumdar D, Goel A, Desai K, Shenoy A. Mature teratoma arising from the sella – case report. Neurol Med Chir (Tokyo) 2001; 41: 356–359. 14. Zavanone M, Alimehmeti R, Campanella R et al. Cerebellar mature teratoma in adulthood. J Neurosurg Sci 2002; 46: 35–38; discussion 8.
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Neuropathology 2015; 35, 44–49
doi:10.1111/neup.12140
Cas e Rep o r t
Adenocarcinoma arising from intracranial recurrent mature teratoma and featuring mutated KRAS and wild-type BRAF genes Eun Soo Kim,1 Mi Jung Kwon,2 Joon Ho Song,3 Dong Hoon Kim2 and Hye-Rim Park2 Departments of 1Radiology, 2Pathology and 3Neurosurgery, Hallym University Sacred Heart Hospital, Hallym University College of Medicine, Anyang, Republic of Korea
Malignant transformation or recurrence of intracranial mature teratoma is an extremely rare occurrence, compared to the usual ovarian counterpart. Previously, yolk sac tumor elements have been considered to be selective progenitors of enteric-type adenocarcinoma arising from intracranial germ cell tumors. However, the present case demonstrates the occurrence of enteric-type adenocarcinoma in recurrent intracranial mature cystic teratoma 12 years after gross total removal, a case of which has not previously been documented in the literature. The 11.5-cm long, dura mater-based tumor on the right fronto-temporal lobe displaced the brain; however, the patient had no neurologic symptoms or discomfort other than pus-like discharge on the scalp. Microscopic examinations revealed a small focus of adenocarcinoma and dysplastic colonic mucosa in the mature cystic teratoma. No immature elements were seen. The cystic wall was almost denuded and showed an exuberant xanthogranulomatous reaction with foreign-body type giant cells engulfing keratin materials and cholesterol clefts, suggesting that chronic inflammation due to repeated cyst wall rupture and the previous resection may contribute to malignant transformation. The adenocarcinoma showed strong immunohistochemical expression of CK20 and p53, but CK7 in patches. The molecular profile of the adenocarcinoma showed a mutation in KRAS and wild-type BRAF, which might be associated with malignant transformation of intracranial mature teratomas. In conclusion, the intracranial mature
Correspondence: Mi Jung Kwon, MD, PhD, Department of Pathology, Hallym University Sacred Heart Hospital, Hallym University College of Medicine, 896, Pyeongchon-dong, Dongan-gu, Anyang, Gyeonggi-do 431-070, Republic of Korea. Email: mulank@ hanmail.net Received 8 April 2014; revised 13 May 2014 and accepted 14 May 2014; published online 11 July 2014.
© 2014 Japanese Society of Neuropathology
teratomas should require long-term follow-up, and clinicians, radiologists and pathologists should be aware of the potential for malignant progression of recurrent intracranial mature cystic teratoma despite gross total resection and no neurologic symptoms. Key words: adenocarcinoma, dura mater, immunohistochemistry, mature teratoma, recurrence.
INTRODUCTION Intracranial mature teratomas are rare extra-neuraxial germ cell tumors, characterized by the presence of highly differentiated adult-type tissues that arise from three germ cell layers.1 Comprising 0.5% of intracranial tumors, intracranial mature teratomas occur most often at the midline of the brain.1 In particular, the pathogenesis and clinical significance of dura-based mature teratomas outside the typical location are unrevealed. Malignant transformation or recurrence of an intracranial mature teratoma is an extremely rare event.1 Enteric-type adenocarcinoma arising from an intracranial mature teratoma is rare, with only one previously reported case.2 However, the adenocarcinoma previously described occurred in mixed germ cell tumors that were composed of yolk sac tumor, immature teratoma, and mature teratoma and not in a pure mature teratoma.2 Because of the co-existence of yolk sac tumors and adenocarcinoma arising from intracranial germ cell tumors, yolk sac tumor elements have been considered to be selective progenitors of enteric-type adenocarcinoma.1,2 The present case is characterized by the first report of the development of enteric-type adenocarcinoma in pure intracranial mature teratoma harboring mutated KRAS and wild-type BRAF genes. These molecular alterations may imply important roles in the malignant transformation of intracranial mature teratoma. In addition, the present case is unique in the recurrent huge mature cystic
Carcinoma in recurrent dural mature teratoma
45
Fig. 1 Sagittal (A) and coronal (B) MRI revealed a large, cylindrical, encapsulated fluid-filled cystic mass that measures approximately 11.5 × 2.5 × 3.0 cm and occupies a previous craniectomy site (white arrowhead) in the right frontal lobe. The mass extends into the right retro-maxillary area, through the greater wing of the right sphenoid bone. Adjacent pachymeningeal enhancement and thickening are observed (white arrows, A–D). Thick or nodular enhancements of the cystic mass were noted at the right intra-orbit (yellow arrow; D), pterygopalatine fossa (yellow arrow; E), infratemporal fossa, masticator space and posterolateral wall of the right maxillary sinus (yellow arrows; F) and were accompanied by bone erosion and perilesional soft tissue invasion.
teratoma that underwent malignant transformation at a tumor removal site 12 years after gross total removal. Herein, we present an exceptional case of adenocarcinoma from recurrent mature cystic teratoma developed in the extra-axial frontal dura growing to a huge mass without clinical awareness.
CLINICAL SUMMARY A 54-year-old Korean man presented with an oozing mass in the right frontal scalp area that had been enlarged and aggravated for 2 weeks. Twelve years previously, he had a 7-cm mature cystic teratoma removed from the same area but did not have follow-up evaluations after the surgery. Physical examination of the right frontal scalp area revealed a firm and fixed mass of approximately 3 cm in diameter; however, no neurological deficits were observed. At the site of the previous craniectomy, MRI showed a large, cylindrical, encapsulated, cystic mass with fluid that measured approximately 11.5 × 2.5 × 3.0 cm. The large mass extended into the right retro-maxillary area, through the greater wing of the right sphenoid bone (Fig. 1A–F). The mass showed diffuse thick enhancement at the peripheral wall and nodular enhancing lesions at the inner and outer portions of the wall. The mass appeared to arise from the dura mater and to encroach on the surrounding bone and soft tissue. The right fronto-temporal lobe of the brain was mildly compressed by the mass (Fig. 1A,D). Thick or nodular enhancement of the cystic mass was observed at the scalp and the dura of the previous craniectomy site in the right frontal lobe, as well as at the right intra-orbit, © 2014 Japanese Society of Neuropathology
pterygopalatine fossa, infratemporal fossa, masticator space, and posterolateral wall of the right maxillary sinus. Perilesional bony erosion, accompanied by surrounding soft tissue invasion, was observed. The adjacent pachymeningeal enhancement and thickening were suggestive of reactive change or pachymeningitis. No abnormal leptomeningeal enhancement and no focal lesion at brain parenchyma were observed by MRI. The patient underwent a gross total resection of the cystic mass. Intraoperative inspection revealed that the mass was adhered to the outer dura and retromaxillary fat pad. The mass was encapsulated and was partially golden-yellow, with a firm consistency. When the mass was opened, pus-like fluid was observed. The overlying skull bone showed hyperostosis with an irregular surface.
METHODS The tumor specimen was fixed in 10% buffered formalin, embedded in paraffin, and cut into 4 μm-thick sections. The sections were stained with HE, and immunohistochemistry was performed using the Discovery XT automated staining system (Ventana Medical Systems, Tucson, AZ, USA), according to the manufacturer’s protocol. The following primary antibodies, and dilutions, were used in immunoperoxidase reactions: anti-CK20 (1:50, Dako, Glostrup, Denmark), anti-CK7 (1:300, Dako), anti-Ki-67 (1:250, clone MIB-1, Dako) and anti-p53 (1:500, clone DO-7, Novocastra, Newcastle, UK). For molecular analysis, the cancerous area was manually microdissected under
46 a light microscope. Genomic DNA was extracted from sections using the QIAamp DNA Mini Kit (QIAGEN, Hilden, Germany). Mutational analyses for KRAS (codon 12 and 13) and BRAF (V600E) genes were performed using real-time quantitative PCR with peptide nucleic acid (PNA)-mediated clamping, using the PNAClampTM KRAS and BRAF Mutation Detection kits (PANAGENE, Daejeon, Korea), according to the manufacturer’s instructions, as previously described.3 Briefly, PNA probes and DNA primers are used together in the clamping reaction. The PNA probe, which has a sequence complementary to wild-type DNA, suppresses the amplification of wild-type target by competitively inhibiting primer binding to wildtype DNA. This results in a preferential amplification of mutant sequences. Positive signals were detected using the fluorescent dye. PCR efficiency was determined by measuring the threshold cycle (Ct) value. Ct values were obtained for the control and mutation assays by observing the amplification plots. Delta Ct (ΔCt) value was calculated as follows, ensuring that the sample and standard Ct values are from the tested sample and clamping control sample. [Standard Ct]-[Sample Ct] = ΔCt. The
ES Kim et al. cut-off ΔCt was defined as 2 for the KRAS and BRAF mutation.
PATHOLOGICAL FINDINGS Macroscopically, the cystic mass was unilocular, with an inner surface that showed grayish irregular fragile nodular lesions. Upon serial sectioning of the cystic mass, a yellowtan cut surface with calcified foci was revealed (Fig. 2A). Microscopically, a mature cystic teratoma with tissues arising from all three germ cell layers, including squamous epithelium, sebaceous and sweat glands, and adipose tissue, was observed (Fig. 2B). Ciliated respiratory type epithelium and salivary-type seromucinous glands were observed (Fig. 2C). Scattered bundles of smooth muscles (Fig. 2D) mixed with mature adipose tissue and bone formation were also observed. In addition, floating colonic mucosa with goblet cells was observed (Fig. 2E). No immature elements were seen. The majority of the cystic lining was denuded, and the fibrotic wall showed a xanthogranulomatous reaction, with foreign-body type giant cells engulfing keratin materials and cholesterol clefts (Fig. 2F).
Fig. 2 (A) The cut surfaces of the cystic mass show a thickened fibrotic wall that contains a grayish-yellow nodular lesion at the inner surface. (B) Squamous epithelium, sebaceous and sweat glands, and adipose tissue are observed at a 40 × magnification. (C) Ciliated respiratory type epithelium and salivary-type seromucinous glands are observed at a 200 × magnification. (D) Scattered bundles of smooth muscles and sweat glands are noted in the fibrous cystic wall (200 × magnification). (E) We noted floating colonic mucosa with goblet cells at a 400 × magnification. (F) The majority of the fibrotic wall shows a xanthogranulomatous reaction, with foreign body-type giant cells engulfing keratin materials and cholesterol clefts (200 × magnification). Scale bars = 250 μm (B) and 50 μm (C–F).
© 2014 Japanese Society of Neuropathology
Carcinoma in recurrent dural mature teratoma
47
Fig. 3 (A) A 0.8 × 0.7 cm cancerous focus (white arrow) is observed in the whitish gray nodular lesion. (B) The tumor infiltrates the cystic wall but does not extend beyond the cystic wall (40 × magnification). (C) The tumor displays well-formed tubular structures and clusters of fused or cribriform glands (100 × magnification). (D) The tumor cells show irregular enlarged nuclei, with prominent nucleoli and coarse chromatin, and the presence of atypical mitosis (400 × magnification). (E) Foci of low-grade dysplastic cells with hyperchromatic and stratified nuclei are observed, which show 7% of Ki-67 labeling index (F) and 100% of p53 expression (G) (400 × magnification). The adenocarcinoma stains diffusely positive for CK20 (H, 200 × magnification) and stains positive for CK7 in patches (I, 100 × magnification). The adenocarcinoma stains positive for Ki-67 (J) and shows strong, diffuse staining for p53 (K) (200 × magnification). (L) Real-time quantitative PCR analysis reveals a mutation of codon 12 of KRAS. Scale bars = 500 μm (B), 100 μm (C, I), and 50 μm (D–H, J–K). , Non PNA; , KRAS #12; , KRAS #13.
The whitish-gray nodular lesion showed a cancerous focus (0.8 × 0.7 cm) that displayed well-formed tubular structures and clusters of fused or cribriform glands infiltrating the cystic wall (Fig. 3A), which did not extend beyond the cystic wall (Fig. 3B). The tumor cells showed irregular enlarged nuclei, with prominent nucleoli and coarse chromatin, and atypical mitosis (Fig. 3C–D). Foci of mildly atypical elongated cells with hyperchromatic and stratified nuclei were observed in the adjacent area (Fig. 3E). Using immunohistochemistry, approximately 7% of those mildly atypical cells showed Ki-67 labeling index (Fig. 3F) and 100% of them showed p53 expression (Fig. 3G), which were favoring low-grade dysplastic cells. The adenocarcinoma stained diffusely positive for CK20 (Fig. 3H) and stained positive for CK7 in patches (Fig. 3I), suggesting enteric differentiation. Approximately 100% of cancer cells stained positive for Ki-67 protein (Fig. 3J) and approximately 100% of the cancer cells stained positive for p53 protein (Fig. 3K). Using real-time quantitative PCR, with PNA-mediated clamping, a mutation in codon 12 in KRAS gene (Fig. 3L) and wild-type BRAF gene were detected in the adenocarcinoma. © 2014 Japanese Society of Neuropathology
Histologic review of the initial specimen slides 12 years ago did not reveal any immature or malignant components within the mature teratoma. Upon these findings, a diagnosis of adenocarcinoma developing in the recurrent intracranial mature cystic teratoma was made and the molecular alterations were identified.
DISCUSSION An intracranial mature teratoma with malignant component is likely to be a borderline malignancy, while an intracranial pure mature teratoma is benign.4 The present case represents an initially histologically proven intracranial mature teratoma may relapse into malignant transformation. The tumor was a huge, cylindrical, encapsulated, cystic mass that originated from the dura covering the right frontotemporal lobe of the previous surgery site and extending into the right retro-maxillary area, compressing the brain. However, the patient showed no neurologic deficits or signs of meningitis, possibly as a result of the chronic incubation period and the slow-growing nature of the tumor.5 The time interval between initial surgery and
48 recurrence was 12 years, which is a long time for recurrence and malignant transformation. Adenocarcinoma may be derived from pre-existing intestinal epithelium within the teratoma; however, the mechanism of malignant transformation of the pre-existing epithelium is unknown. In our case, the cystic wall showed the denuded cystic lining and an exuberant xanthogranulomatous reaction with foreign body-type giant cells engulfing keratin materials and cholesterol clefts, suggesting that chronic inflammatory reaction due to repeated cyst wall rupture and the previous resection may result in dysplasia and contribute to malignant transformation.6,7 Histologically, the presence of dysplasia on the adenocarcinoma background may indicate that the cancerous focus might progress through a dysplasia-carcinoma sequence.8,9 In the present case, p53 immunoreactivity was diffuse in the dysplasia and the adenocarcinoma. Interestingly, in the presented case, we observed malignant transformation in recurrent dura mater-based teratoma that harbored a genetic alteration. The identified KRAS mutation has previously been reported in intestinal-type adenocarcinoma arising in ovarian mature teratoma.8 To the best of our knowledge, this is the first report of the identification of wild-type BRAF and a mutation in KRAS in intestinal-type adenocarcinoma originating in intracranial mature teratoma. KRAS and BRAF mutations are observed in approximately 30–54% and 10–18%, of colorectal adenocarcinomas, respectively.3,9,10 The mutation in KRAS may play an important role in the malignant transformation of mature teratoma, simulating the molecular events that underlie the carcinogenesis of colorectal carcinoma.8,9 In the presented case, the KRAS mutation and p53 dysregulation may be involved in the carcinogenesis events of the intracranial mature teratoma. Dura mater-based mature teratomas are rarely observed, although they are large tumors measuring up to 8 cm in length.5,11–14 The present tumor measured 11.5 cm at its longest, as the dura-based location provided the space to grow. The origin and pathogenesis of intracranial germ cell tumors are controversial. Zhao et al.11 have speculated that the dura mater may be the origin of extra-axial mature teratomas, whereas Sano4 has explained the development of germ cell tumors in the CNS by the “misinvolvementmisenfoldment” hypothesis during embryogenesis. The abnormal migration of embryonic cells into the dura mater may be responsible for the occurrence of dura-based mature teratomas and residual embryonic cells may be related to recurrence.11 In summary, the enteric-type adenocarcinoma arising in recurrent intracranial mature teratoma had a KRAS mutation and wild-type BRAF and showed p53 overexpression, which might be associated with malignant transformation of intracranial mature teratomas. The pre-
ES Kim et al. sent case suggests that intracranial mature teratomas should require long-term follow-up and clinicians, radiologists and pathologists should be aware of the potential for malignant progression of recurrent intracranial mature cystic teratoma despite gross total resection and no neurologic symptoms.
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