Merkel cell tumour: case reports and review

Abstract

Merkel cell carcinoma, a small-cell undifferentiated/neuroendocrine carcinoma, is a highly invasive primary malignant neoplasm of the skin that may arise from Merkel cells or an epithelial precursor cell. One tenth of all cases affect the eyelids and periocular region, typically in the elderly population. The presentation is generally as a painless erythematous nodule with telangiectatic blood vessels and often intact overlying skin. The rarity of Merkel cell carcinoma of the eyelid can lead to delay in diagnosis and treatment of this tumour. In the present paper, the authors illustrate the aggressive nature of Merkel cell carcinoma, and the importance of early and wide surgical treatment and close follow-up. They discuss the role of rapid paraffin histology compared to frozen section. METHODS Three cases are described, discussing the clinical presentation, diagnosis and treatment, with a review of the pathology. RESULTS All three patients were female, presenting with rapidly growing upper eyelid tumours 20 mm in size; one case had paraffin sections suggesting incomplete clearance when frozen section had appeared clear; exenteration was required. The other two cases had lymph node involvement at one and two months post wide local excision. All patients remain alive at follow-up of 6, 4.6, and 2 years, respectively. DISCUSSION The cases illustrate the aggressive nature of the tumour, the unusual tarsal involvement and the typical pathology. Sampling errors associated with limited frozen section control of excision may be avoidable by the use of rapid paraffin histology. The highly invasive nature of this tumour requires close follow-up following resection.