Intraepithelial neoplasia of the anal canal in hemorrhoidal tissue: a study of 19 cases.

The investigators report the clinical and pathologic features of 19 cases of intraepithelial neoplasia occurring in the anal canal mucosa of routinely excised hemorrhoidal tissue, a condition that has been infrequently described. The patients were 12 women and seven men having an age range of 21 to 74 years (mean, 48 years). Two patients had coexistent anogenital condylomata acuminata. Leukoplakia of the hemorrhoidal surface was noted in two patients. Intraepithelial neoplasia arose in the transition zone of the anal canal of 11 cases, in the squamous zone of three cases, and in both sites of five cases. All were high-grade intraepithelial neoplasms; one was classified moderate to severe dysplasia, 17 exhibited severe dysplasia/carcinoma in situ, and one contained microinvasive carcinoma. Both keratinizing and cloacogenic type neoplasms were observed. Associated koilocytotic atypia was identified in 16 cases (84%). In situ hybridization for human papillomavirus (HPV) messenger RNA demonstrated HPV RNA sequences in seven of nine neoplasms (78%) studied by that technique (five HPV type 16, one HPV type 18, and one coinfection with HPV types 6 and 18). Eighteen patients had no clinically evident recurrent or progressive disease at mean follow-up of 6.6 years. Residual/recurrent intraepithelial neoplasia was noted in one patient at 1, 2, 5, and 49 months posthemorrhoidectomy. Our data indicate that incidentally discovered high-grade intraepithelial neoplasia present in hemorroidal tissue is a clinically nonaggressive lesion frequently associated with HPV infection. Hemorrhoidectomy alone is curative in most cases.