An Immunohistochemical Study of Mixed Tumor of the Skin

An asymptomatic tumor developed on the upper lip of a 63‐year‐old man. Histologically, the tumor contained glandular and cystic structures forming many branching lumina, and many scattered single cells in an abundant mucoid to chondroid stroma. The tumor was diagnosed as mixed tumor of the skin. Histochemically, the cells composing the tubular structures contained neutral mucopolysaccharides and the stroma, acid mucopolysaccharides. Immunohistochemically, the cells of the glandular and cystic structures showed epithelial and sweat gland differentiation (EMA‐, CEA‐, BRST‐1‐and BRST‐2‐positive), while the cells scattered in the stroma showed a tendency toward myoepithelial differentiation (S‐100 protein‐ and vimentin‐positive).