1 July 2005 Case of the Week #12
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We thank Dr. Ins Raoelfils, Centre Jean Perrin, Clermont-Ferrand, France for contributing this case. This case was reviewed in May 2020 by Dr. Jennifer Bennett, University of Chicago and Dr. Carlos Parra-Herran, University of Toronto.
Case of the Week #12
A twenty two year old woman had a large right ovarian mass, which was excised.
Immunohistochemistry images: PLAP, AFP, c-Kit / CD117
The immunohistochemistry was interpreted as PLAP positive, AFP negative, c-Kit positive.
What is your diagnosis?
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Diagnosis: Dysgerminoma of the ovary
Dysgerminoma of the ovary is an uncommon tumor, representing less than 1% of ovarian malignancies. They usually affect young patients, with 80% under age 30 years. 15% have bilateral tumors. Approximately 5% are associated with gonadal dysgenesis, androgen insensitivity or pseudohermaphroditism. Some cases appear to represent progression from gonadoblastomas (Virchows Arch 2005;447:603). Patients with dysgerminomas typically present with low stage and have a 95% survival. Metastases can occur to the opposite ovary, retroperitoneal lymph nodes or the peritoneal cavity, but often dont affect survival. Dysgerminomas are typically treated with surgery and chemotherapy, and not radiotherapy, which may impair fertility in these usually young patients (National Cancer Institute Treatment Summary). Dysgerminomas may rarely transform to a yolk sac tumor (Mod Path 1995;8:881), and may be mixed with other germ cell tumors, such as choriocarcinoma, yolk sac tumor or embryonal carcinoma, which worsens the prognosis. Thus, it is important to adequately section these tumors, and search for different looking areas of the tumor.
Dysgerminomas are grossly solid and nodular tumors of variable size. They are gray-pink, resembling cerebral cortex, and commonly have hemorrhage and necrosis. Microscopically, they are composed of tumor cells separated by fibrous stroma with T lymphocytes. The tumor cells are large with well defined cell borders. The cytoplasm contains glycogen, and the nuclei are central, vesicular and contain one or more prominent nucleoli. Granulomas may be present.
The differential diagnosis includes yolk sac tumor, undifferentiated carcinoma, clear cell adenocarcinoma (usually in post-menopausal women, PLAP negative), lymphoma, melanoma, granulosa cell tumor and metastatic breast carcinoma. Careful review of the histology of multiple sections, special stains and clinical history are helpful in distinguishing these other tumors. Dysgerminomas are immunoreactive for PLAP, c-Kit and vimentin. They may be focally positive for hCG in giant cells, and focally positive for cytokeratin. They are negative for AFP. Recent reports indicate that Oct4, a transcription factor involved in the regulation of pluripotency during embryonic development, is sensitive and relatively specific for dysgerminomas (AJSP 2004;28:1341).
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