Merkel cell: Friend or felon

Abstract

Merkel cells are perceived as tactile receptors within skin and oral mucosa containing abundant intermediate filaments but lacking characteristic condensation of tonofilaments, hence are also referred to as non-keratinocytes. Merkel cell carcinomas (MCCs) are primary aggressive neuroendocrine neoplasms occurring in elderly individuals. Toker in 1972 reported MCC of skin pointing towards sweat glands as the source of origin which was later rectified by Tang with the aid of ultrastructural studies as Merkel cells to be a lineage of such tumours. Normally, Merkel cells are abundant in the gingiva and vermillion border of the lip and thus these are the common sites for this neoplasm. Histopathologically, MCC mimics varied other carcinomas, hence requiring a thorough diagnostic protocol. We present a case of challenging histopathology which on immunohistochemical analysis with a unique cytokeratin profile and neurofilament staining pattern helped in reaching a definitive diagnosis.