Merkel cell carcinoma:An infrequent but highlymalignanttype of skin cancer. Characteristically startsina sun-exposed area (of the head,neck,armsor legs) in whites 60-80 years of age as a firm, painless, shiny lump that can be red, pink, or blue in color and vary in size from less than a quarter of aninch(a halfcm) to more than two inches (5 cm) in diameter. The tumor grows rapidly and often metastasizes (spreads) to other parts of the body. Even relatively small tumors are capable ofmetastasis, particularly to the regional (nearby)lymph nodes. Merkelcellcarcinomafollows anaggressivecourse like that of melanoma, and has a predilection to spread to (in order of frequency) liver,bone,brain, lung, andskin. Theprognosis(outlook) is accordingly poor.
"Merkel" is often misspelled as "Merkle." Thediseaseis named for the German anatomist andpathologistFriedrich Sigmund Merkel (1845-1919) and is also called神经内分泌carcinomaof the skin.
