Clear-cell dermal duct tumour: another distinctive, previously underrecognized cutaneous adnexal neoplasm.

Aims: To describe 13 examples of clear cell dermal duct tumour, a neoplasm previously underrecognized in the literature.

Methods And Results: Thirteen examples of a neoplasm that we have named clear-cell dermal duct tumour were studied histopathologically and immunohistochemically. Histopathologically, all lesions consisted of mostly dermal neoplasms mainly composed of multiple solid aggregations of clear cells involving the dermis. Although the neoplasms were mostly solid, ductal structures were identified in all cases. Immunohistochemically, neoplastic cells were immunoreactive for MNF116 and AE1/AE3 cytokeratins, but not for CAM5.2 or cytokeratin 7. Epithelial membrane antigen, carcinoembryonic antigen and glial cystic disease fibrillary protein 15 decorated the ductal structures, but neoplastic cells were negative. In contrast to some other clear cell neoplasms of the skin, which may be associated with diabetes mellitus, none of our cases of clear cell dermal duct tumour developed in a diabetic patient.

Conclusions: We consider these neoplasms to be clear cell dermal duct tumours for the following reasons: (i) the neoplasms were mostly composed of multiple solid aggregations of epithelial clear cells; (ii) neoplastic aggregations mostly involved the dermis; (iii) in some cases, neoplastic aggregations of conventional poroid cells were intermingled with the aggregations of clear cells; (iv) ductal structures were identified within some neoplastic aggregations; (iv) small areas of necrosis en masse were seen in some neoplastic aggregations; and (v) the stroma of the neoplasm was scant.