Mature ovarian teratomas rarely undergo transformation into malignancy. Carcinomas, mostly squamous cell carcinoma, are the most common malignancy arising in mature cystic teratoma. In the present report we describe a 13-year-old girl who developed a large mass in her ovary. Fine needle biopsy identified intestinal type mucinous adenocarcinoma, which was also identified in the full surgical specimen. Extensive sampling of the surgical specimen also identified areas of mature cystic teratoma. Interestingly, molecular analysis of DNA extracted from various components of the lesion identified KRAS mutation in the carcinoma, borderline mucinous tumor and benign intestinal-type epithelium but not in the epidermal component of the teratoma. To the best of our knowledge this is the first report of KRAS mutation in mucinous carcinoma originating in mature cystic teratoma. We discuss the importance of extensive tissue sampling to differentiate between carcinoma originating in teratoma and metastatic colorectal carcinoma to the ovary. Additionally, the identification of KRAS mutation in the morphologically benign intestinal-type epithelium indicated that it is an early event in the carcinogenic sequence and that the molecular pathway of carcinogenesis in teratoma is similar to that in the carcinogenic process of somatic tissue.
Keywords: Adenoma-Carcinoma sequence; KRAS mutation; mucinous carcinoma; teratoma.
© 2013 The Authors. Pathology International © 2013 Japanese Society of Pathology and Wiley Publishing Asia Pty Ltd.