MERKEL CELL-CARCINOMA OF THE EYELID

The Merkel cell is part of the dendritic cell population of the epider mis, and studies suggest it has a role as a slowly adapting mechanorec eptor involved with mediating the sense of touch. Merkel cells can giv e rise to malignant neoplasms, one tenth of which occur in the eyelid and periocular area, and manifest as painless erythematous nodules, wi th overlying telangiectatic blood vessels. Merkel cell carcinoma can m imic other malignant lesions, and the diagnosis can be difficult. One third of the tumors recur, and there is a high rate of metastasis. The estimated 5-year survival rate is 38%. Initial treatment should be ag gressive, including surgical resection, with consideration of postoper ative radiation. Merkel cell carcinoma responds to chemotherapy, but r outinely recurs on cessation of treatment. Two cases are presented to illustrate the typical presentation of Merkel cell carcinoma and the i mportance of electron microscopy and immunohistochemical studies.