Merkel Cell Carcinoma.

Merkel cell carcinoma is a primary neuroendocrine tumour of the skin arising from the dermis and extending into the subcutis, occurring commonly in sun-exposed areas of the head and neck of the elderly. Clinically, non-specific erythematous or violaceous firm nodules or small plaques which may be surrounded by small adjacent satellite tumours are seen. Diagnosis of Merkel cell carcinoma is difficult by light microscopy alone and need of ancillary techniques like electron microscopy and immunohistochemistry may be necessary.