The pathogenesis of inflammatory polyps.

Eighty-six consecutive colonic resection specimens for inflammatory bowel disease were studied to determine the modes of inflammatory polyp formation. The two major groups of inflammatory polyps were polypoid mucosal tags due to undermining ulceration and mature inflammatory polyps composed of mucosa, muscularis mucosae, and a submucosal core. Mature inflammatory polyps were derived from polypoid mucosal tags after regeneration and the adjacent mucosa showed regenerative changes and submucosal scarring. The study confirms that ulceration which undermines the muscularis mucosae is the major precursor of inflammatory polyps.