MSH: Discrete abnormal tissue masses that protrude into the lumen of the DIGESTIVE TRACT or the RESPIRATORY TRACT. Polyps can be spheroidal, hemispheroidal, or irregular mound-shaped structures attached to the MUCOUS MEMBRANE of the lumen wall either by a stalk, pedunculus, or by a broad base.,NCI: A growth that protrudes from a mucous membrane.,NCI: A protruding growth attached to the underlying tissue by a broad base or a thin stalk, which can be either inflammatory, hamartomatous, or neoplastic.,NCI: A usually exophytic mass attached to the underlying tissue by a broad base or a thin stalk. Polyps can be neoplastic or non-neoplastic. Neoplastic polyps usually represent proliferations of the epithelium, and are commonly seen in the gastrointestinal tract. Polyps of the gastrointestinal tract are often called adenomas, are associated with dysplasia, and may eventually transform into carcinomas. Non-neoplastic polyps may be inflammatory, degenerative, or the result of malformations.