Carcinoma is a type of cancer that begins in the cells that either make up the skin or the cells that line the organs, according to WebMD. They can affect many different parts of the body.
Carcinomas are abnormal cells that begin to divide uncontrollably, states WebMD. They may stay in the location where they started or spread to other parts of the body. Carcinomas that stay in the area they began are known as carcinoma in situ, while carcinomas that spread are named by the part of the body that they spread to. Common types of carcinomas include basal cell carcinoma, squamous cell carcinoma and renal cell carcinoma.