Purpose: To evaluate the clinical and histopathologic characteristics of Merkel cell carcinoma (MCC) of the eyelid.

Design: Retrospective case series and literature review.

Participants: Three consecutive patients with MCC of the eyelid who were referred to the Ocular Oncology Unit of Leiden University Medical Center, Netherlands.

Methods: Clinical records and histopathologic material of patients with eyelid MCC were reviewed. The clinical presentation and treatment were evaluated.

Main outcome measures: Clinical and histopathologic description of eyelid MCC, with histologic proof of spontaneous regression of the tumor.

Results: Three patients with MCC of the eyelid were included. Diagnosis was made by pathologic investigation and immunohistochemistry (S100, cytokeratin 20, epithelial membrane antigen, chromogranin). Two of the patients showed histologically proven complete spontaneous regression after nonradical excision of the tumor. After local excision, none of the MCCs demonstrated local recurrence, without regional or distant metastases. Mean clinical follow-up was 50 months.

Conclusions: Nonocular MCC is known to recur in 66% of patients and to be lethal in almost 33%. Merkel cell carcinoma of the eyelid is a rare malignancy that can not be recognized clinically. Clinical differential diagnosis must be made with a chalazion, and histopathologic differential diagnosis must be made with small cell carcinomas. Close follow-up of these patients is advised because of the potential high recurrence rate and lymphatic spread. The immunologic phenomenon of spontaneous regression points out the importance of the immune system in this disease.