Testicular Mixed Germ Cell Tumor with Concurrent Embryonic-Type Neuroectodermal Tumor and Nephroblastoma.

Both embryonic-type neuroectodermal tumor and nephroblastoma arising as somatic-type malignancies are rare, particularly nephroblastoma. Concurrent embryonic-type neuroectodermal tumor and nephroblastoma have only been reported once in literature, identified in metastatic pelvic lymph nodes in association with a mixed germ cell tumor. Herein, we report the first concurrent embryonic-type neuroectodermal tumor and nephroblastoma within the primary testicular tumor, arising associated with a mixed germ cell tumor. A 36-year-old man presented with a 4.5 cm right testicular mass. He underwent right orchiectomy. Gross examination revealed a well-circumscribed, solid to cystic mass confined to the testis (pT1). Histological examination demonstrated a mixed germ cell tumor composed of teratoma (40% of the tumor mass), seminoma (10%), embryonal carcinoma (2.5%), and yolk sac tumor (2.5%), with associated germ cell neoplasia in situ. Additionally, two somatic-type malignancy components were identified, including embryonic-type neuroectodermal tumor (40%) and nephroblastoma (5%). The embryonic-type neuroectodermal tumor consisted of primitive neural tubules, rosettes, and blastemal cells. The nephroblastoma was composed of tubules, blastemal cells, and stromal cells. Immunohistochemically, the embryonic-type neuroectodermal tumor showed diffuse positivity for SOX11, with focal expression of synaptophysin and CD99, while the nephroblastoma was positive for PAX8 and WT1. The patient developed metastasis to a retroperitoneal lymph node 1 month after the orchiectomy, subsequently received chemotherapy, and is alive without metastatic disease at 13 months of follow-up.