Incipient merkel cell carcinoma: a report of 2 cases.

Merkel cell carcinoma is a malignant skin tumor with a poor prognosis that primarily affects photoexposed areas of elderly patients. Tumor size is a very strong prognostic factor, with much better outcomes associated with small lesions, measuring less than 1cm. However, such lesions are rarely seen in the clinic in view of the rapid growth of this tumor. We report 2 cases of incipient Merkel cell carcinoma. Both cases of incipient Merkel cell carcinoma measured approximately 5mm in diameter. One tumor was confined to the epidermis and papillary dermis on the nose of a 79-year-old man and the other was located in the deep dermis, almost in the hypodermis, on the buttock of an 82-year-old woman. In both cases, the lesions had appeared weeks earlier. The first tumor seemed to originate in the dermoepidermal junction whereas the second originated almost in the hypodermis. Although the lesions were at a similar disease stage and had a similar size, their different locations within the dermis highlight once again the controversy about which cells give rise to Merkel cell carcinoma. The precursor cells could feasibly be Merkel cells in the first case but not in the second.