A case of spermatocytic tumor in the testis
A male in his 50s presented to his urologist with a mass in his right testis. Contrast-enhanced magnetic resonance imaging revealed a round testicular mass approximately 23 mm in diameter with homogeneous contrast enhancement and diffusion restriction. Blood tests showed human chorionic gonadotropin < 2.3 mIU/mL, alpha-fetoprotein 3.5 ng/mL (normal range, 10-20 ng/mL), and lactate dehydrogenase 157 U/L (normal range, 120–220 U/L). A high orchiectomy was performed. A well-demarcated, white-colored mass was observed on gross examination of the testis. Histologically, the tumor exhibited three types of round cells of varying sizes, and the nuclear chromatin of intermediate and giant cells displayed granular or filamentous patterns. Mitotic figures were scattered, with minimal lymphocytic infiltrates. The presence of germ cell neoplasia in situ (GCNIS) remained uncertain. Immunohistochemistry revealed SALL4 positivity, partial weak positivity for c-KIT, but negativity for OCT-3/4 and D2-40 in tumor cells. Consequently, a diagnosis of spermatocytic tumor (ST) was made. ST is classified by the World Health Organization as one of the GCNIS-unrelated germ cell tumors and is rare, accounting for approximately 0.6-1.0% of testicular germ cell tumors. Although microscopically similar to seminomas, STs, and seminomas differ in clinicopathologic features. Accurate diagnosis relies on recognizing this rare entity, careful observation of hematoxylin-eosin staining and the adjunctive use of immunohistochemistry.
