[Penile skin metastasis of gastric carcinoma associated with prostate carcinoma: a case report].

Skin metastasis of internal carcinoma is a rare situation and its risk is reported as 0.7-9%. The site of skin metastasis is more popular at upper part of the body such as neck and face. We report a case of perineal and penile skin metastases of gastric carcinoma associated with prostatic carcinoma. A 72-year-old man, who underwent total gastrectomy for gastric carcinoma 4 years ago, was found to have sclerotic change at perineal and penile skin. As his serum PSA level was 10.6 ng/ml, transrectal prostate biopsy and penile skin biopsy were performed. The prostate tissue pathologically demonstrated moderately differentiated adenocarcinoma and it was positive for both anti-PSA and anti-CEA antibody by immunohistochemical staining. The skin tissue was found to be infiltrative adenocarcinoma, negative for PSA and positive for CEA, which was compatible with the primary gastric carcinoma specimen. The patient had been treated for 7 months with administration of Doxifluridine and injection of LH-RH agonist, but died for progression of gastric carcinoma. A risk of skin metastasis of gastric carcinoma is reported as 6%, however, its metastasis to perineal and penile skin is the first case reported in the literature.