Merkel cells in extraocular sebaceous carcinoma.

Background: Mature sebaceous glands do not contain Merkel cells. Neither do sebaceous tumors in the vast majority of cases. Recently, however, it was showed that rare sebaceous adenomas with a carcinoid-like or labyrinthine pattern can contain intratumoral Merkel cells. Our purpose in this study is to examine for the presence of Merkel cells in extraocular sebaceous carcinomas.

Methods: Nineteen cases of extraocular sebaceous carcinoma were retrospectively studied with cytokeratin 20.

Results: One out of 19 cases (5.3%) contained Merkel cells in the basal layers of the tumoral nests of a sebaceous carcinoma from the cheek of a 76-year-old woman.

Conclusions: Merkel cells are rarely evident in extraocular sebaceous carcinoma, and therefore, their evidence does not exclude this diagnosis.