A carcinoma arising from merkel cells located in the basal layer of the epidermis and occurring most commonly as a primary neuroendocrine carcinoma of the skin. merkel cells are tactile cells of neuroectodermal origin and histologically show neurosecretory granules. The skin of the head and neck are a common site of Merkel cell carcinoma, occurring generally in elderly patients. (Holland et al., Cancer medicine, 3d ed, p1245)