Malignant Leydig-cell tumor of the testis diagnosed by fine-needle aspiration using ThinPrep technique.

Leydig cell tumors (LCT) are rare sex cord-stromal tumors that account for 2-3% of all testicular tumors. Approximately 10% of LCTs shows evidence of malignant behavior. We present a case of LCT with severe atypia diagnosed by fine-needle aspiration (FNA) in a 49-year-old man who presented with gynecomastia and right testis enlargement.