Skin involvement as the presenting sign of internal carcinoma. A retrospective study of 7316 cancer patients.

From tumor registry data of 7316 cancer patients, we found 367 cases (5.0%) with skin involvement. Skin involvement was present at the time of presentation in 92 patients (1.3%), only 26 of whom had remote metastases. Skin involvement was the first sign of cancer in 59 patients (0.8%); 22 had direct extension of their tumor into the skin, 20 had local metastases, and 17 had distal metastases. Direct invasion was most common with breast cancer and second most common with oral cavity cancer. Local metastases were also most frequently caused by breast cancer but occurred in surgical scars in three women with pelvic cancer and in perianal abscesses in one patient with rectal carcinoma as well. Except for metastases from unknown primary sites, distant metastases were rare as presenting signs, and their origins were widely distributed. Our data show that internal cancer uncommonly presents with skin involvement. Nevertheless, an index of suspicion should be maintained and biopsy performed, particularly for nonhealing ulcers, persistent indurated erythema, and unexplained skin nodules.