Objective: High-resolution anoscopy (HRA) is a useful screening tool for anal intraepithelial neoplasia (AIN), although reputedly challenging for interpretation of suspected lesions.
Materials and Methods: All consecutive patients who underwent biopsies for at least 1 lesion suspicious for AIN during HRA from November 2010 to March 2012 were prospectively included. The characteristics (borders, staining with acetic acid and Lugol iodine solution, and patterns of epithelium and vascularization) of the lesions detected during HRA were compared with histology.
Results: A total of 168 suspicious anal lesions were biopsied and analyzed in 103 patients (68% men, mean age ± standard deviation = 49.8 ± 9 y, 57% positive status on human immunodeficiency virus infection). According to histology, 41.7% of the lesions were high grade, 34.5% were low grade, and 23.8% were nondysplastic. Lesions with irregular epithelial pattern (or irregular vascularization) were twice as likely to be high grade compared with lesions with regular epithelial pattern (or regular vascularization). The incidences of acetic acid-induced whitening were 91.4%, 94.8%, and 70% among the high-grade AIN, low-grade AIN, and nondysplastic samples, respectively. Among the high-grade AIN, 62.9% were not stained by Lugol solution (vs 31% of the low-grade AIN). The positive predictive value of a combination of these simple morphological criteria was 68.6%.
Conclusions: Several simple morphological criteria are significantly associated with high-grade AIN and are found less often in low-grade AIN. A combination of these morphological criteria provides sufficient positive predictive value to guide biopsy placement during HRA.