Virilism and ectopic expression of HSD17B5 in mature cystic teratoma

Mature cystic teratoma (MCT) is rarely involved in the overproduction of steroid hormones in contrast to sex cord stromal tumors. A 31-year-old woman visited our hospital with hirsutism, hoarseness, and hair loss from the scalp. Serum testosterone and free-testosterone levels were 7.3 ng/ml and 2.3 pg/ml, respectively, which were markedly in excess of the age adjusted female standard levels. Basal blood levels of steroid hormones and serum levels of 17-hydroxyprogesterone at 1 h after intravenous injection of adrenocorticotropic hormone demonstrated that 21-hydroxylase deficiency was not the underlying cause of her virilization. A subsequent chromosomal test with G-banding revealed a karyotype of 46XX. Magnetic resonance imaging revealed a mass in the left ovary, which was subsequently diagnosed as MCT. Detailed pathological analysis of the tumor indicated that it was comprised of skin components, sweat glands, with hair and fat texture, glandular epithelium and fibrous connective tissue, consistent with the characteristic composition of MCT. Immunohistochemical analysis demonstrated marked immunoreactivity of 17beta-hydroxysteroid dehydrogenase (HSD17B5), an enzyme that can convert androstenedione to testosterone. Following surgical removal of the tumor, testosterone and free testosterone levels were markedly decreased (0.3 ng/ml and 0.4 pg/ml, respectively) and other symptoms abated. In conclusion, this is the first report of an ovarian MCT associated with clinical virilization caused by the ectopic production of testosterone possibly because of an overexpression of intratumoral HSD17B5.