The hypertrophied anal papilla: recognition on air-contrast barium enema examinations.

Anal papillae are acquired structures that arise from the base of the rectal columns of Morgagni at the dentate line. They enlarge in response to congestion, irritation, injury, or infection. Although anal papillae are commonly seen endoscopically, they are rarely demonstrated radiographically. Three cases are reported of hypertrophied anal papillae that were demonstrated on air-contrast barium enema examinations. Radiographically an enlarged anal papilla appears as a smooth polyp located just inside the anal verge. Endoscopically it is differentiated from an adenomatous polyp by its white appearance and its origin from the lower (squamous) aspect of the dentate line in the anal canal. Hypertrophied anal papilla should be included in the differential diagnosis of a smooth mass located near the anal verge, especially in a patient with a history of chronic and irritation or infection.