Mucinous carcinoma of the skin with apocrine-type differentiation: immunohistochemical studies.

We investigated the pathway of differentiation in a case of mucinous carcinoma of the skin (MCS) arising on the right temple of a 70-year-old man. Histopathologic findings of the tumor showed evidence of apocrine-type differentiation such as distinctive decapitation secretion. Additionally, by employing a panel of antibodies, the immunohistochemical staining pattern of tumor cells was shown to be compatible with that of apocrine glands. Although the differentiation of this neoplasm remains controversial, the findings in our case suggest apocrine differentiation.