A Case of Unclassified Sex Cord-Stromal Tumor Containing hCG-Positive Cells

We present a case of unclassified sex cord-stromal testicular tumor with lung metastasis. A 48-year-old man consulted our hospital for left testicular enlargement that began 3 years ago. Computed tomography revealed a heterogeneously enhanced left testicular tumor 11 cm in diameter and a 5 mm metastatic lung tumor. The human chorionic gonadotropin (hCG) level was elevated (141.6 mU/ml), whereas the levels of α-fetoprotein (AFP) and LDH were normal. The external genitalia were normal and gynecomastia was not observed. Left high orchiectomy followed by 3 cycles of BEP chemotherapy (bleomycin, etoposide, and cisplatin) every 4 weeks was performed. The pathology of the excised specimen was unclassified sex cordstromal testicular tumor containing hCG-positive cells. On immunohistochemistry, the tumor cells were partly positive for AE1/AE3, hCG, and calretinin. Vimentin was diffusely positive, but OCT3/4, SALL4, GATA3, and CK7 were negative. After BEP treatment, the metastatic lung lesion disappeared. Unclassified sex cord-stromal testicular tumor is a rare disease and its treatment has not been established. Thus, further accumulation of cases is needed.