Sweat duct proliferation associated with aggregates of elastic tissue and atrophodermia vermiculata: a simulator of microcystic adnexal carcinoma. Report of two cases.

Microcystic adnexal carcinoma (MAC) is a rare, usually solitary, slowly growing, yet aggressive neoplasm with a tendency for local recurrences. Herein, we present two patients who had been histopathologically diagnosed as suffering from MAC on both cheeks since childhood, an unlikely scenario. Both from a clinical and from a histopathological point of view, our two cases showed some similarities with those previously described in patients with Nicolau-Balus syndrome, Rombo syndrome, and so-called eccrine-pilar hamartoma. Common to all these latter disorders are the round aggregations of elastic tissue in the papillary dermis, a histopathological feature which was also found in our patients. However, to our knowledge, the presence of a MAC-like ductal proliferation embedded in sclerotic stroma and extending to the deep dermis has not been previously described. Dermatologists and dermatopathologists should be aware of this disorder to avoid overdiagnosis of and inappropriate treatment for MAC.