Performance of p16INK4a immunocytochemistry as a marker of anal squamous intraepithelial lesions.

BACKGROUND: Protein p16(INK4a) immunocytochemistry (ICCp16) has the potential to reveal lesions at risk of progression to anal cancer. This study examined measures of diagnostic validity of ICCp16 in HIV-positive patients treated at the Tropical Medicine Foundation of Amazonas in the coloproctology outpatient clinic. METHODS: One hundred ninety HIV-positive patients were consecutively enrolled in 2007 and 2008. All patients underwent anal cytologic sampling to perform ICCp16 in conventional and GluCyte (Synermed International, Westfield, Indiana and S¸ao Paulo, Brazil) smears and also for genotyping of human papillomavirus (HPV). Patients were then subjected to anal biopsies monitored by high-resolution anoscopy. Hematoxylin-eosin and immunoperoxidase p16 (clone 6H12) stains were performed in slides with biopsied and cytological specimens, respectively. HPV genotyping on anal scrapings was performed by a polymerase-chain reaction (PCR)-based method. The immunochemical findings were compared with histopathological and PCR results in contingency tables and analyzed by nonparametric tests. Measures of diagnostic validity of ICCp16 were calculated. Statistical significance was set at P ≤ .5. RESULTS: There was no statistically significant association between the immunochemical results (conventional or GluCyte smears) and histopathological or HPV genotyping findings (P > .05). In the best scenario, ICCp16 presented 31% sensitivity and 81% specificity for the diagnosis of anal squamous intraepithelial lesion (ASIL) and 30% and 66%, respectively, for the diagnosis of infection with high-risk HPV. CONCLUSIONS: There was no association between ICCp16 results and histopathological findings nor between ICCp16 and HPV genotyping. ICCp16 showed poor sensitivity and moderate specificity for the diagnosis of ASIL or high-risk HPV.

High-resolution anoscopy in the diagnosis of anal cancer precursor lesions in renal graft recipients.

BACKGROUND: Renal graft recipients are one of the population groups known to be at high risk of developing anal cancer. This study investigated the presence of subclinical anal squamous intraepithelial lesions and the diagnostic ability of high-resolution anoscopy in detecting these lesions in renal graft recipients followed-up in Manaus. METHODS: In a cross-sectional study, 50 renal graft recipients were interviewed and submitted to high-resolution anoscopy with biopsies of acetowhite lesions or of the anal transition zone mucosa when acetowhitening was absent. Considering the histopathological reports of the examined anal specimens as the gold standard, the diagnostic validation and precision measures of high-resolution anoscopy were calculated as well as the prevalence of anal squamous intraepithelial lesions in the studied population. RESULTS: In 42 renal graft recipients with satisfactory histopathological readings, prevalence of anal squamous intraepithelial lesions or condyloma acuminatum (ASIL-ACU) was 23.81%. Sensitivity of high-resolution anoscopy was 100%; specificity, 65.63%; positive predictive value, 47.62%; negative predictive value, 100%; and kappa coefficient, 0.48. CONCLUSIONS: With a prevalence of 23.81% of subclinical ASIL-ACU lesions, the studied renal graft recipients had all these lesions detected by high-resolution anoscopy, notwithstanding most anal transition zone acetowhitened biopsied areas did not reveal histopathological aspects of anal cancer precursor lesions or condyloma acuminatum. Therefore, greater experience with the diagnostic tool was felt necessary to enhance its positive predictive value, specificity and diagnostic precision.