Abstract

Testicular choriocarcinoma is the least common subtype of germ cell tumors (GCTs): pure choriocarcinoma accounting for less than 1% of all GCTs and 8% of mixed GCTs containing a choriocarcinoma component. Choriocarcinoma disseminates by both hematogenous and lymphatic pathways and most commonly to lungs, liver, gastrointestinal tract and brain. Cutaneous metastases are extremely rare with only 25 cases reported in the world literature. Herein, a 20-year-old male presented with right testicular pain and swelling for 3 weeks. Ultrasound showed an enlarged heterogeneous right testis with internal calcification. Serum beta-human chorionic gonadotropin was 135,918 mIU/mL and lactate dehydrogenase was 437 units/L while alpha-fetoprotein was normal. Two cutaneous lesions were also noted during the physical examination and subsequently biopsied: 1) 2cm crateriform plaque with central keratotic plug with hemorrhagic crust on the occipital scalp; 2) 1 cm firm subcutaneous nodule with overlying bright red 1-2mm papules on the left posterior shoulder. Histopathologically, both lesions showed similar morphology: composed of syncytiotrophoblasts and mononucleated trophoblasts surrounding hemorrhagic areas, which were highlighted by SALL4 (focal) and GATA3 immunostains. A diagnosis of metastatic choriocarcinoma was rendered. In addition to cutaneous metastases, further imaging studies showed likely metastases to retroperitoneal lymph nodes, right kidney, lungs and brain. The patient has been receiving chemotherapy for 2 months with surgical management being planned. Although cutaneous metastases of testicular choriocarcinoma are extremely uncommon, it is important to recognize and include this entity in the differential diagnosis as the skin biopsy may provide the initial and sole tissue specimen for confirmatory pathological diagnosis prior to treatment.

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