Several sections of this left ovarian tumor, including cyst wall and solid mass, are examined. The inner lining of the cyst tumor is composed of keratinized squamous epithelium with underlying adnexal structures. Several sections taken from solid mass within the cystic tumor reveal moderately differentiated invasive squamous cell carcinoma. Mature squamous epithelium changing into dysplastic epithelium and transitioning to invasive squamous cell carcinoma is identified in one section. In some areas, tumor is seen penetrating the capsule and reaching the inked external surface of the tumor. Mesodermal or endodermal elements are not identified. This is a mature cystic teratoma with malignant transformation to squamous cell carcinoma.
Malignant transformation in a mature cystic teratoma of the ovary is rare. The reported incidence of mature cystic teratoma is 1.2 -14.2 cases per 100,000 per year and the proportion of cases in which malignant transformation occurs is 0.17-2%. The malignant transformation is more common in postmenopausal women. More than 80% of malignant transformations are squamous cell carcinoma arising from the ectoderm; the rest are carcinoid tumors or adenocarcinomas. High risk human papilloma virus infection may be associated with ovarian squamous cell carcinoma. Squamous cell carcinoma antigen (SCCA), CA125, CA19-9 and CEAR raised in many patients with malignant transformation of ovarian teratoma to squamous cell carcinoma. Prognostic factors include capsular invasion, rupture, tumor dissemination, ascites and adhesions. Surgical treatment of squamous cell carcinoma arising in mature cystic teratoma is similar to that of epithelial ovarian cancer.
Hackethal A et al. Squamous-cell carcinoma in mature cystic teratoma of the ovary: systemic review and analysis of published date. Lancet Oncol. 2008 Dec;9(12):1173-80