Extraocular cutaneous sebaceous carcinoma in a patient with Muir-Torre syndrome: special emphasis on histologic and dermoscopic features

Abstract

Cutaneous sebaceous carcinoma can be classified into periocular and extraocular and can occur as part of Muir Torre syndrome. It is usually a pink-red or yellow solitary nodule, mainly located in the head and neck region. According to the Literature, dermoscopy is characterized in most cases by yellow color, polymorphic vessels and ulceration. We performed a review of the Literature and we found 14 papers describing the dermoscopic features of 33 sebaceous carcinomas, to which we added a case that we have recently observed. Compared to the data of the Literature and in particular to the latest published reviews, we found that milky-red areas are frequently observed in CSC (47% of the cases) and can be added to the main dermoscopic features for the diagnosis. Histology showed, in our case, some features that were consistent with a cutaneous sebaceous carcinoma with a secretory pattern, and other features that were instead consistent with a non-secretory pattern. This was probably due to the fact that the lesion we observed was a moderately differentiated and not well-differentiated cutaneous sebaceous carcinoma. The presence of a cutaneous sebaceous carcinoma should always alert the clinician on the possible association with Muir-Torre syndrome and immunohistochemistry for mismatch repair genes defects can help in the diagnostic pathway.