Mixed angiosarcoma, clear cell adenocarcinoma and mature teratoma elements in an ovarian tumor: a case report and literature review.

Malignant transformation of a mature teratoma in the ovary is a rare event, with an approximate rate of only 1-2%. Here, we report an ovarian tumor with a unique combination of epithelial and non-epithelial malignant components, including mature teratoma elements. A 59 year-old postmenopusal woman underwent total hysterectomy and bilateral salpingo-oophorectomy to remove a huge solid mass of the right ovary. The ovarian tumor was 16 × 12 × 4.5 cm in dimensions, composed of red-brown and greyish-white tissue with several cystic areas. Microscopically, atypical cells immunopositive for both CD31 and CD34 formed irregular ectatic vascular patterns with a high MIB-1 labeling index in red-brown areas. In contrast, tubule-cystic and papillary structures were lined by HNF-1β-immunopositive atypical cuboidal and hobnail cells with clear cytoplasm in greyish-white areas. In addition, normal-looking epithelial and stromal components, including mature squamous, cuboidal and ciliated epithelial cells, and adipose tissues, were observed in red-brown areas, suggesting an ovarian tumor combining angiosarcoma, clear cell adenocarcinoma, and mature teratoma features. We could demonstrate identical X-chromosome inactivation patterns among all three components by human androgen receptor gene (HUMARA) assays, pointing to complex inter-relationships regarding their pathogenesis. These observations suggest that a malignant tumor composed of two characteristic phenotypes arose in mature teratoma.