Mucinous metaplasia rarely develops in the non-neoplastic skin or its appendages, and almost exclusively confined to the genitalia, palms and soles. Similarly, mucinous metaplasia is quite uncommon in the cutaneous neoplasms and only few cases of clear cell hidradenomas and squamous cell carcinomas with mucinous metaplasia have been reported in the literature. Here we report a new case of clear cell hidradenoma with mucinous metaplasia in the forehead. Our immunohistochemical analysis revealed MUC5AC in the mucinous metaplastic cells of this tumor as in the extramammary Paget's disease, and expression of this gastric foveolar epithelial mucin core protein in these two neoplastic conditions seem to related to their common apocrine origin.