Cystic sebaceous neoplasms in Muir-Torre syndrome.

Cystic sebaceous neoplasms have been seen only in patients with Muir-Torre syndrome (MTS) and have recently been characterized as marker lesions of MTS. Histologically, these lesions form a spectrum of tumors ranging from benign cystic adenomas to proliferative cystic sebaceous tumors. We describe 2 proliferative cystic sebaceous tumors in a 53-year-old man whose workup revealed colonic adenocarcinoma and other sebaceous tumors consistent with MTS. Both the chest wall and the left thigh masses were grossly cystic, measuring 1.0 and 1.5 cm, respectively. Histologic sections demonstrated well-circumscribed cystic neoplasms located in the deep dermis and subcutaneous tissue. Each had a focally infolded cyst wall composed of immature basaloid cells with prominent nucleoli and mitoses, consistent with a proliferative cystic sebaceous tumor. Recognition of cystic sebaceous neoplasm by pathologists and communication to clinicians of its strong association with MTS is of diagnostic importance.