[911] Epithelioid Trophoblastic Tumor of the Testis: The Widening Spectrum of Primary Testicular Trophoblastic Neoplasia

Muhammad T Idrees, Thomas M Ulbright. Indiana University School of Medicine, Indianapolis, IN

Background: Epithelioid trophoblastic tumor (ETT) is a rare neoplasm thought to originate from gestational trophoblast cells that differentiate toward intermediate trophoblast cells normally found in the chorion laeve (fetal membrane). Similar appearing tumors in the lungs of patients with metastatic gestational choriocarcinoma after intensive chemotherapy have been described as “atypical choriocarcinoma.” ETT has not, however, been reported as a primary testicular neoplasm, although other trophoblastic tumors, including placental site trophoblastic tumor and cystic trophoblastic tumor, are recognized in the testis. We therefore present four cases of ETT arising within mixed germ cell tumors (GCT) of the testis.
Design: An electronic data search from departmental consultation files was performed for all testicular trophoblastic tumors. H&E and IHC stains were performed in all cases. Pertinent clinical information and followup were obtained from clinical notes.
Results: We identified four cases of ETT in orchiectomy specimens performed for testicular masses in patients 19–36 years old. All ETTs were components of mixed GCTs, averaging 5–10% of the tumor volume. The predominant component in two cases was seminoma; one yolk sac tumor and one embryonal carcinoma. Microscopically, the ETTs consisted of squamoid monophasic trophoblast cells in cohesive epithelioid nests with abundant eosinophilic cytoplasm, lacking the biphasic pattern characteristic of choriocarcinoma (Fig. 1A). One had an interesting mixed pseudoglandular and nested pattern (Fig. 1B–1C). The most useful immunostain was inhibin (Fig. 1D), which was positive in all cases, while HCG was positive in three.

Conclusions: We present the morphologic features of a unique tumor of germ cell origin that expand the spectrum of testicular trophoblastic neoplasia.
Category: Genitourinary (including renal tumors)

Monday, March 4, 2013 1:00 PM

Poster Session II # 186, Monday Afternoon


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