Primary Mucinous Carcinoma of the Skin

BACKGROUND Primary mucinous carcinoma is a rare primary adnexal neoplasm of the skin with a high recurrence rate. OBJECTIVE To improve the recognition of this clinical entity and aid in establishing the origin of this tumor. METHODS Two cases of this tumor were reported and investigated histopathologically and histochemically. Furthermore, some mucinous carcinomas arising from the breast or gastrointestinal tract were compared with this tumor. RESULTS Both cases showed no evidence of primary neoplasms as a source of metastasis and had characteristic findings of primary mucinous carcinoma of elongated cords and small lobules of epithelial cells floating in lakes of sialomucin. The origin of this tumor seemed to be an eccrine sweat gland. CONCLUSION This tumor should be resected widely and, at least, the breasts and gastrointestinal tract should be investigated for primary lesions.