Endocrine mucin-producing sweat gland carcinoma: a study of three cases and CK8, CK18 and CD5/6 immunoexpression

Endocrine mucin-producing sweat gland carcinoma is a cutaneous adnexal tumor that is rarely reported in the literature. We identified only 29 previously reported cases. All these cases share some clinical morphologic and immunohistochemical features. Among the immunohistochemical markers, cytokeratins 5/6, 8 and 18 (CK5/6, CK8 and CK18) had not been previously studied in this tumor. Although studies with cytokeratin Cam5.2 exist, we know at present that this marker does not correspond to antibodies CK8/18, but rather to CK7 and CK8. We studied three examples of endocrine mucin-producing sweat gland carcinoma with 18 immunostains. Our cases showed an immunoprofile CK8+, CK18+, CK5/6- (or only focally positive), CK7+, GCDFP-15+ (2 cases), estrogen receptor+, progesterone receptor+, HER2-, neuron-specific enolase + (2 cases), anti-synaptophysin+, chromogranin A +, CD56 variable (1 case +, 1 case-), CD57-, anti-human D2-40- (two cases), p63- or focally positive, smooth muscle actin + with variable pattern of expression and smooth muscle myosin heavy chain expressed in a peripheral discontinuous layer in some nodules, but absent in most.