Michiaki Kimura

Cytologic Findings of Epithelioid Trophoblastic Tumor of the Uterus

BACKGROUND Epithelioid trophoblastic tumor (ETT) is a rare entity within trophoblastic tumors. It is difficult to recognize ETT because of its epithelioid appearance. CASE A 35-year-old female, 5 years after pregnancy, experienced genital bleeding 2 months prior to consulting us. Preoperative laboratory data showed a slightly elevated serum level of human chorionic gonadotropin (hCG). A cytologic cervical smear revealed large, polygonal, atypical cells. These cells had mononucleate, ovoid, irregularly enlarged and hyperchromatic nuclei with 1 or 2 conspicuous nucleoli. The cytoplasm was thin and abundant, with a distinct cell membrane, and sometimes showed vacuolation. The patient was diagnosed with uterine cancer, and hysterectomy was performed. The tumor was present in the uterine corpus, measuring 3 x 2.5 x 2.5 cm. Histologically, it was composed of mainly mononuclear tumor cell nests resembling intermediate trophoblastic cells with zones of hyaline material. Immunohistochemically, the tumor was positive for cytokeratin and placental alkaline phosphatase but negative for hCG and human placental lactogen. The tumor was subsequently diagnosed as ETT. CONCLUSION It was difficult to make a definitive diagnosis of ETT using only a cytologic specimen. The diagnosis of ETT is facilitated by a combination of cytologic, histopathologic and clinical findings.