A carcinoma is any malignant cancer that arises from epithelial cells. Carcinomas invade surrounding tissues and organs and may metastasize (spread) to lymph nodes and distal sites. Carcinoma in situ (CIS) is a pre-malignant condition, in which cytological signs of malignancy are present, but there is no histological evidence of invasion through the epithelial basement membrane. There are many different types of carcinoma (lung, breast, bowel, etc) and signs, symptoms, diagnosis and treatment all depend on the specific carcinoma.