[Anal cytology for screening of pre-neoplasic lesions].

Background: High grade intra-epithelial neoplasias (HAIN) are probable precursors of anal carcinoma, with association to high-risk types of Human Papillomavirus (HPV). This progression could be related to severity of the dysplasia and, albeit not yet confirmed, treatment of these lesions would prevent the evolution to cancer. Standardization and improvement of screening methods should therefore be essential to treat or prevent precursor lesions, mainly in patients at risk such as seropositives to Human Immunodeficiency Virus (HIV). The aim of this study was to evaluate if anal cytology, with a cytobrush, could be useful to screen clinic and pre-clinic lesions provoked by HPV.

Methods: Brushes were used to obtain smears from the anal canal of 102 HIV-positive patients with proctologic complaints. There were 86 males and 16 females with a mean age of 37 years. HPV infection was denied by 33 patients, 14 had treated anal warts in the past, 28 had condylomas in the anal verge, seven had internal clinical lesions and 20 had both internal and external condylomas. The smears were submitted to Pappanicolaou and hematoxilin-eosin stains to identify cytological changes including HAIN. T CD4+ lymphocyte counts were also evaluated to check if the immunologic status caused more advanced dysplasia.

Results: One smear only proved insufficient. All the others revealed cellular patterns varying from normality to HAIN. Low grade AIN (LAIN) occurred in 30 and HAIN in 13 patients. One patient with HAIN, without a history of HPV infection in the past, presented an anal canal ulcer which at biopsy was diagnosed as invasive squamous-cell carcinoma. T CD4+ cells averaged 281/mm(3) for LAIN patients and 438/mm(3) for HAIN patients. Analyses disclosed a statistical difference, showing that despite expectations, more advanced dysplasias occurred in patients with higher counts of T CD4+ cells. This fact demonstrated that isolated systemic immunity did not seem to interfere in the genesis of these lesions, suggesting that aspects of local immunity should be studied. Statistical analyses by a 2x2 table revealed sensibility of 74% and specificity of 61%.

Conclusion: Results suggest that cytology could be used to diagnose anal cancer precursors.