Tumors of trophoblastic derivation other than
choriocarcinoma are very rare in the testis but have been reported on occasion in association with other
germ cell tumors. Their morphologic spectrum is analogous to the
trophoblastic tumors of the female genital tract including epithelioid
trophoblastic tumor (ETT) and
placental site trophoblastic tumor (PSTT). Herein we report our experience with 8 cases of
trophoblastic tumors of testicular origin that lacked the features of
choriocarcinoma; these included 4 ETTs, 1 PSTT, 1 unclassified
trophoblastic tumor (UTT), 1 partially regressed
choriocarcinoma with a monophasic morphology, and 1 hybrid
tumor showing a mixture of
adenocarcinoma and a UTT. All
tumors occurred in young men 19 to 43 years old. Five arose de novo within the testis (2 ETTs, 1 UTT, 1 regressing
choriocarcinoma, and the hybrid
tumor) as a component of mixed
germ cell tumors, and 3 (2 ETTs and 1 PSTT) were found in metastatic sites after
chemotherapy. The trophoblastic component was minor (5% to 10%) in 6
tumors but was 95% of 1 metastatic
tumor (ETT) and 50% of the hybrid
tumor. Other
germ cell tumor elements were identified in all cases, most commonly
teratoma. The ETTs consisted of nodules and nests of squamoid trophoblast cells showing abundant eosinophilic cytoplasm, frequent apoptotic cells, extracellular fibrinoid material, and positivity for p63 and negativity for
human placental lactogen (HPL). The PSTT showed sheets of discohesive, pleomorphic, mononucleated trophoblast cells that invaded blood vessels with fibrinoid change and were p63 negative and HPL positive. The UTT showed a spectrum of small and large trophoblast cells, some multinucleated but lacking distinct syncytiotrophoblasts, and was patchily positive for both p63 and HPL. The hybrid
tumor had ETT-like and adenocarcinomatous areas that coexpressed
inhibin and GATA3 but were negative for p63 and HPL, leading to classification of the trophoblastic component as UTT. Seven of the patients were alive and well on follow-up (8 to 96 mo; median, 39 mo), whereas the patient with the hybrid
tumor died of liver
metastases at 2 years. Our study verifies that
trophoblastic neoplasms often having the features of nonchoriocarcinomatous gestational
trophoblastic tumors may arise from the testis, occur either in the untreated primary
tumor or in
metastases after
chemotherapy, and should be distinguished from
choriocarcinoma given what appears to be a less aggressive
clinical course.