Adult Granulosa Cell Tumor With Low-Level Amplifications of JAK2, ERBB3, CDK4, and MDM2: A Rare Testicular Tumor.

Testicular adult granulosa cell tumors (AGCTs) are exceptionally rare neoplasms that are thought to be the male counterpart of ovarian granulosa cell tumors (GCT). Here, we present a 50-year-old African American male who initially presented with right testicular pain and swelling, with ultrasound revealing a 2.0-cm heterogeneous hypoechoic lesion along the upper pole/interpolar right testicle with internal vascularity. Microscopic examination was consistent with AGCT, demonstrating monomorphic cells with elongated nuclei containing numerous small grooves, resembling ovarian granulosa cells, and scant cytoplasm arranged in trabeculae and sheets. Immunohistochemical stains of the tumor were positive for inhibin, vimentin, and weakly positive for calretinin, S100, and Ki67 (10%). Next Generation Sequencing (NGS) showed low-level amplifications of JAK2, ERBB3, CDK4, and MDM2. No gene fusions or mutations were identified. The patient underwent a radical orchiectomy and remains alive and disease-free at 42 months following diagnosis.