Leukoplakia of the anal canal.

Two cases of leukoplakia of the anal canal are presented, with illustrations of the typical gross and microscopic appearance. The lesions were asymptomatic, and were discovered by routine rectal examination. Histological findings included hyperkeratosis and acanthosis extending cephalad from the anal verge to the dentate line. Followup after 3 and 15 years revealed no evidence of dysplastic changes, and a review of the literature did not uncover any reported cases with dysplasia or with documented evolution to malignancy. There is little evidence that leukoplakia of the anal canal is premalignant but patients should be followed carefully, since the natural history of this rare lesion is unknown.