Merkel cell carcinoma (cutaneous neuroendocrine carcinoma) is a highly mali
gnant, neuroendocrine skin tumor. It mostly occurs in elderly patients in t
he sun-exposed skin of the head and neck and the extremities. Merkel cell c
arcinomas develop as fast-growing dermal tumors. They are characterized by
a high frequency of lymph-node metastases (50%) and local recurrences (25-7
7%). The 5-year survival rate is 30-74%. Histology reveals uniform, round c
ells with a small cytoplasmic rim expressing cytokeratin 20, neurofilament,
synaptophysin, chromogranin, and neuron-specific enolase. Ultrastructurall
y, 100-200 nn electron dense granules are typical findings. Wide surgical e
xcision, followed by radiotherapy, is the treatment of choice. Regional lym
ph-node metastases should be treated by radical lymph-node excision and rad
iotherapy. In advanced metastatic Merkel cell carcinoma, a remission can be
achieved by different chemotherapy schedules or the somatostatin analogue
octreotide. However, the prognosis remains poor. The current knowledge abou
t this disease and guidelines for effective diagnosis and treatment are giv
en.