Ki-67 expression in anal intraepithelial neoplasia in AIDS

AIDS is one of the most important risk factors for progression and recurrence of anogenital condyloma. In a previous work, we observed that patients with warts and high-grade AIN (HAIN) had recurrences more frequently than did patients with warts without AIN. The mechanisms of this increased incidence of high-grade lesions in AIDS are not known. We studied the expression of the proliferative marker Ki-67 by immunohistochemical methods, in specimens of anal condyloma from HIV+ patients to clarify whether its expression can be associated to the grade of AIN. A retrospective study of histological specimens. University referral unit. 34 patients were divided into two groups: (1) condylomas with low grade AIN (LAIN), with 25 patients; and (2) condylomas with HAIN, with 9 patients. In this latter group we examined two areas: 2A (HAIN area) and 2B (LAIN area). The immunohistochemical reaction for Ki-67 was done on histological sections. Slices were lightly stained with hematoxylin, to help us in Ki-67 positive cell counting. The percentage of Ki-67 marked nuclei was calculated. We applied one-way variance analysis for statistics. The mean number of Ki-67 positive cells in group 1 was 19.68 +/- 10.99; in group 2 (area A) it was 46.73 +/- 10.409; and in area B it was 36.43 +/- 14.731. There were statistical differences between groups 1 and 2A and between groups 1 and 2B. Ki-67 positive cells predominated in the lower layer in LAIN. Positive Ki-67 cells were found in all layers in group 2A, and in group 2B they predominated in the two lower or in all layers of the epithelium. Our results suggest that LAIN areas (using routine staining techniques) in HAIN can have a biological behavior more similar to HAIN.