Merkel Cell Carcinoma

Merkel cell carcinoma is a rare, highly aggressive primary cutaneous tumor, predominantly affecting older patients. The pathogenesis is associated with either Merkel cell polyomavirus infection or UV-mediated damage caused by chronic sun exposure: virus-positive and virus-negative Merkel cell tumors are characterized by two different patterns of multiple DNA mutations. Virus-positive tumors are mainly diffuse in the Northern hemisphere, while virus-negative tumors have higher incidence in Australia with a predilection of fair-skinned population. Merkel cell tumor presents with asymptomatic, rapidly growing, red or violet cutaneous nodule. Histology and immunohistochemistry are necessary to confirm the diagnosis. The management of Merkel cell tumors requires a multidisciplinary approach. Surgery or definitive radiotherapy of the primary Merkel cell tumors are either treatment options for patients with localized MCC. Immune checkpoint inhibitors represent the preferred treatment option for metastatic tumors.