AbstractThe incidence, clinical features, histogenesis, and treatment of extramammary Paget's disease (EMPD) are reviewed. This unusual skin lesion is associated with an underlying adnexal neoplasm in about 50% of cases. Also, the incidence of distant organ malignancies of EMPD is higher than expected by chance. Even in the absence of a recognizable underlying cancer, EMPD may occasionally produce distant metastases, indicating the malignant potential of this condition. Histochemical, immunohistological, and lectin binding studies demonstrate that the cell of origin of EMPD is the exocrine cell of sweat glands. Although EMPD may arise from ec-crine cells, derivation from apocrine cells appears more common. The treatment of the primary lesion, by wide margin excision, is fraught by a high recurrence rate. Chemosurgery may reduce local relapse of EMPD. The value of adjuvant radiation therapy is unestablished. Chemotherapy has induced remission in 2 cases of advanced EMPD and needs testing in clinical trials.