Case report of a malignant Brenner tumor with hyperestrogenism.

A rare malignant Brenner tumor of the ovary presenting with hyperestrogenism in a 79 year old woman was examined immunohistochemically and by light and electron microscopy. High pre-operative serum and urinary estrogen concentrations, low serum luteinizing hormone (LH) and follicle-stimulating hormone (FSH) levels, and histologically confirmed atypical endometrial hyperplasia suggested the presence of hyperestrogenism. The reduction in serum and urinary estrogen and the increase in serum LH and FSH concentrations after tumor removal confirmed that the tumor was synthesizing estrogen. Histologically, the malignant element was predominantly a squamous cell carcinoma. Transitional cell carcinoma was partially found on the cyst wall. There was a spectrum of morphologic changes between benign and malignant elements with an intermediate area with a proliferating Brenner tumor. Immunohistochemically, only the carcinoembryonic antigen was positive exclusively on the malignant element as well as in the microcyst in the benign epithelial cord, whereas all of the markers for germ cell tumors were negative. The ultrastructural features of the stromal cells were of two types: fibroblasts and steroid-producing cells. The latter type of cells might correspond morphologically to estrogen-producing cells. The present case is the fourth report showing a malignant Brenner tumor combined with apparent hyperestrogenism.