Metastatic testicular choriocarcinoma of the skin. Report and review of the literature.

Choriocarcinoma is a malignant growth of trophoblastic cells characterized by secretion of human chorionic gonadotropin. Choriocarcinoma usually arises from fetal trophoblasts and rarely arises from germ cells in the testis or ovary or derives from dedifferentiation of other carcinomas. Skin metastasis of choriocarcinoma is rare: only seven cases have been reported in the English and Japanese literature. We report the case of a 22-year-old Japanese man with pure choriocarcinoma of the testis who developed skin metastases that presented as multiple reddish nodules. Microscopic examination of both the primary lesion of the testis and the cutaneous metastasis demonstrated the typical histologic features of pure choriocarcinoma. The patient died 3 months after the initial onset of skin metastasis. Review of the literature indicates that skin metastasis of choriocarcinoma usually occurs as a nodular lesion with the histologically typical feature of the primary disease and signals of poor prognosis.