Merkel cell carcinoma: the clinical course.

Merkel first discovered the cells named after him in the snout skin of voles in 1875. These cells are thought to originate from the neural crest and act as mechanoreceptors. When they have undergone malignant change, the neurosecretory granules in the cytoplasm may release various polypeptides, suggesting that the tumor is an APUDoma. In a computer search of the literature 121 cases were identified. It was revealed that the most common lesion is an erythematous nodule arising in the face or lower limb and occurring predominantly in women in their late 60s. The regional nodes became involved in half the patients, and the three-year survival was approximately 60%. Two unusual cases, in women 72 and 73 years old respectively, with metastasizing lesions that responded to a combination of surgery and radiotherapy are reported, and the literature is discussed.