International Journal of Gynecological Pathology 29:423–426, Lippincott Williams & Wilkins, Baltimore r 2010 International Society of Gynecological Pathologists Case Report Sertoli Cell Tumor With Benign Peritoneal Implants Associated With Gonadoblastoma Giovanna A. Onida, M.D., Luisanna Bosincu, M.D., Ph.D., Salvatore Dessole, M.D., Alina Nicolae, M.D., Ovidiu Preda, M.D., Paolo Cossu-Rocca, M.D., Jose Aneiros-Fernandez, M.D., and Francisco F. Nogales, M.D., Ph.D. Summary: We present a unique case of bilateral gonadoblastoma in a 23-year-old patient with Swyer syndrome. The gonadoblastoma on both sides underwent synchronous neoplastic transformation, into a stage I germinoma in the right streak gonad and a highly differentiated Sertoli cell tumor in the left one. The latter was associated with a myriad of microscopic, Sertoli cell implants on the peritoneal surface, which were considered benign as they had a high grade of differentiation, minimal proliferative activity, and an absence of invasion. Most probably, the pathogenesis of this abdominal dissemination was iatrogenic, with implantation occurring mechanically as a result of the multiple laparoscopic biopsies performed on both of the streak gonads 2 months before the abdominal surgery. The pathogenesis of other benign abdominal implants is discussed. Key Words: Swyer syndrome—Gonadoblastoma—Sertoli cell tumor—Peritoneal implants—Laparoscopy—Iatrogeny. Gonadoblastoma is a mixed neoplasm composed of germ cells, identical to those found in intra- tubular germ cell neoplasia and undifferentiated sex cord cells. It is almost invariably associated with the presence of a Y chromosome, and it is found in various sexual dysgenesis syndromes. Although it is known that in 20–30% of cases the atypical germ cells in gonadoblastoma are the precursors of various germ cell tumors (1), there has been only 1 report of the sex cord component associated with the development of a sex cord stromal neoplasm, namely a well-differentiated Sertoli cell tumor (2). We present a unique case of bilateral gonado- blastoma that underwent synchronous neoplastic transformation into both a germinoma and a highly differentiated Sertoli cell tumor. The latter was associated with microscopic, benign, omental Sertoli cell tumor implants that were possibly iatrogenically sown onto the peritoneal surface during an earlier laparoscopy during which multiple biopsies were taken. This has not been reported earlier. CASE REPORT A 23-year-old patient was admitted to the inferti- lity clinic: Her menarche occurred at the age of 15 years but was followed by oligomenorrhea. On external examination, she had an unambiguous female phenotype albeit with poor breast develop- ment. Her external genitalia had a normal appear- ance but internal examination showed a hypoplastic uterus. Ultrasonography failed to show follicular activity in the gonads. Serum gonadotropin levels 423 DOI: 10.1097/PGP.0b013e3181dc7c2e From the Department of Pathology and Obstetrics and Gynecology (G.A.O., L.B., S.D., P.C-R.), Universita` degli Studi di Sassari, Sardinia, Italy; and Department of Pathology and Obstetrics and Gynecology (A.N., O.P., J.A-F., F.F.N.), Facultad de Medicina, Granada, Spain. Address correspondence and reprint requests to Francisco F. Nogales, MD, PhD, Department of Pathology, Facultad de Medicina, Av Madrid 11, 18012 Granada, Spain. E-mail: fnogales@ugr.es.