Primary neuroendocrine carcinoma ("Merkel cell tumor") of the eyelid: A report of two cases

BACKGROUND: Merkel cell tumor is an uncommon, aggressive neoplasm of the skin, now regarded as a neuroendocrine carcinoma. Eyelids are among the sites where it can develop, often mimicking a benign process. The purpose of this report is to describe two new cases and to discuss briefly the problems of diagnosis and treatment. METHODS: Two patients with Merkel cell tumor of the eyelids are described. In both cases, the original clinical diagnosis was chalazion. Progressive growth of the lesion identified it as a tumor some 2-7 months after it was first noticed. The patients were treated by surgical excision of the tumor tissue, and only one by a course of local radiotherapy. The visual acuity was measured with Snellen fractions. The dose of local radiotherapy is given in cGy. RESULTS: Histopathological and immunohistochemical studies identified the lesion as a neuroendocrine carcinoma, consistent with Merkel cell tumor. The natural history was marked by aggressive behavior in one case, and by a delayed recurrence in the other, requiring different therapeutic approaches. CONCLUSION: Merkel cell carcinoma of the eyelid is a tumor that ophthalmogists should be aware of, as early diagnosis is a prerequisite for successful treatment. Rapid recurrence of any chalazion in a middle-aged or elderly patient should therefore prompt its histological examination to exclude the possibility of a malignant tumor.