Carcinomas are malignancies arising from epithelial cells, which line the surfaces of organs, glands, and body cavities. These cells form the majority of tissues in organs such as the skin, lungs, breasts, and gastrointestinal tract, making carcinomas the most common type of cancer encountered clinically. The epithelial origin explains their characteristic patterns of local invasion and potential to metastasize via lymphatics. Understanding this origin is crucial during surgical excision to ensure complete removal with clear margins and appropriate lymph node assessment. Proper identification guides prognosis and treatment planning.

Reference: Robbins Basic Pathology, Kumar et al., 10th Edition.