MCC also known as neuroendocrine carcinoma of the skin, is rare, with around 1500 new cases per year in the US. MCC is usually a cancer of mature adults, many with a history of significant sun exposure. It has recently been linked to a virus (Merkel cell polyomavirus) that most adults have been exposed to during their lifetimes. It is thought that an interaction of the viral DNA and ultraviolet light from the sun can lead to formation of this cancer later in life. Patients with Merkel cell carcinoma are not contagious. Due to the rarity of MCC, no large studies have been performed, and no clear treatment guidelines have been developed for this malignancy. MCC can appear as a pink bump on the skin that grows quickly to form a red, bleeding mass. Treatment includes excision of the skin tumor by Mohs micrographic surgery or wide excision. Radiation therapy is often added, although a definite benefit has not been proven for Stage 1a patients with a clean sentinel lymph node biopsy (SLNB). Prognosis depends on the stage of the disease at the time of diagnosis. Small tumors (<2 cm) removed surgically before metastasis can be cured in up to 90% of patients. If the MCC has already metastasized, the prognosis can be poor. Merkel cell carcinoma is treatable, particularly if caught early. Research indicates that MCC is RT (radiotherapy) sensitive. Many people have beaten this aggressive cancer, and new treatments are being tested now.
Because the disease is so rare and no one specialty treats patients with this type of skin cancer, treatment is inconsistent. Head and neck surgeons have one protocol; surgical oncologists have another. It is often misdiagnosed as basal-cell cancer and long delays before diagnosis are common as patients are passed from physician to physician.