Ki-67 expression in anal intraepithelial neoplasia in AIDS.

Context: 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.

Objective: 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.

Design: A retrospective study of histological specimens.

Setting: University referral unit.

Sample: 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).

Main Measurements: 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.

Results: 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.

Conclusions: Our results suggest that LAIN areas (using routine staining techniques) in HAIN can have a biological behavior more similar to HAIN.