Immunosuppression
The incidence of MCC is increased in conditions with defective immune functions such as malignancy, HIV infection, and organ transplant patients, etc. Conversely, patients with brisk immune response have been shown to have improved prognoses. This is suspected to be due to the inability of the body to defend itself from infection by or reactivation of MVC. The body of data indicating the importance of immune function in MCC pathogenesis has been exploited for the development of immunotherapies discussed below. Diagnosis
Diagnosis of MCC begins with a clinical examination of the skin and lymph nodes. Following clinical exam, definitive diagnosis of Merkel cell carcinoma (MCC) requires examination of biopsy tissue to identify its histopathologic features. An ideal biopsy specimen is either a punch biopsy or a full-thickness incisional biopsy of the skin including full-thickness dermis and subcutaneous fat. On light microscopy, MCC shows basaloid tumor nests with neuroendocrine features ("salt and pepper" chromatin, scarce cytoplasm, and brisk mitotic activity). In addition to standard examination under light microscopy, immunohistochemistry (IHC) is also generally required to differentiate MCC from other morphologically similar tumors such as small cell lung cancer, the small cell variant of melanoma, various cutaneous leukemic/lymphoid neoplasms, and Ewings sarcoma. Neuroendocrine molecular markers such as synaptophysin or chromogranin A are characteristic of MCC and other neuroendocrine tumors, while other markers such as PAX5 or cytokeratin 20 can distinguish MCC from these tumors. Longitudinal imaging may also help in ruling out a diagnosis of metastatic small cell lung cancer.
Notable patients
Avigdor Arikha – Paris-based painter and art historian
David Brudnoy – Boston talk radio host
Al Copeland – New Orleans entrepreneur, powerboat racer
Al Davis – Principal owner of the Oakland Raiders of the National Football League
Ed Derwinski – U.S. Representative from Illinois and 1st Secretary of Veterans Affairs
Leonard Hirshan – Showbusiness agent and manager. Max Perutz – Nobel Prize–winning chemist
Lindsay Thompson – Former Premier of Victoria, Australia
Joe Zawinul – Jazz-fusion keyboardist and composer
John Fitch – Race car driver and road safety pioneer
Carl Mundy – 30th Commandant of the United States Marine Corps
Geoffrey Penwill Parsons – Pianist
Maria Bueno – Tennis player

References
External links
 Media related to Merkel cell carcinoma at Wikimedia Commons
National Cancer Institute. "Merkel Cell Carcinoma". National Institutes of Health (US). Archived from the original on 2010-12-21. Retrieved 2011-01-20.