Merkel cell carcinoma: case report and literature review.

BACKGROUND Merkel cell carcinoma is an aggressive neuroendocrine cell carcinoma arising in the epidermis of patients aged >60 years. This lesion is found in sun-exposed areas and presents as a small violet raised nodule. It is usually painless and rapidly growing. Although its clinical presentation and characteristic histology are usually sufficient, immunohistochemical features are helpful in making an accurate diagnosis. CLINICAL CASE We present the case of a 62-year-old male with epidermoid carcinoma of the lung who was treated with surgery and local radiation for 2 months. He presented a painless 8-cm subcutaneous mass of some weeks of evolution, without inflammatory signs. Computerized tomography demonstrated a mass of probable lymph node origin. Fine-needle aspiration biopsy (FNAB) reported malignant cells and excisional surgery of the mass was performed, revealing a subcutaneous Merkel cell carcinoma. CONCLUSIONS Merkel cell carcinoma is a rare entity that develops in mature patients, often in sun-exposed areas, and presents cutaneous injury in intact skin. Definitive diagnosis is done using immunohistochemistry.