A Boy with 46,XX Karyotype (SRY Double-positive) and a Leydig Cell Tumor.

Leydig cell tumors are the most common type of testicular sex cord stromal tumors. The presence of the Y chromosome is associated with tumor risk in sex development disorders (DSD), however tumor development without Y chromosome is extremely rare. A 16-year-old boy diagnosed with Leydig cell tumor due to a mass in the right testis was referred after the right orchiectomy. On physical examination, the left testis was 10 mL, and there was a labial residue in penoscrotal region. Bilateral gynecomastia was present. The karyotype was 46,XX and SRY was double-positive on fluorescent in situ hybridization analysis. Ifosfamide, carboplatin and etoposide chemotherapy was initiated due to the Leydig cell tumor. Here, we report the first pediatric case having 46,XX testicular DSD with double-positive SRY and a Leydig cell tumor.