Objective: Anal high-grade squamous intraepithelial lesion (HSIL) may precede invasive cancer and can be detected clinically or during high-resolution anoscopy (HRA). The aims of this study were to compare the characteristics of HSIL discovered by HRA or in a surgical specimen without clinically visible lesion when diagnosed versus macroscopic HSIL when first diagnosed and then to compare their progression to invasive cancer.
Patients and methods: Clinical records of all patients with at least one HSIL lesion confirmed by histology and evaluated by HRA in a single center between September 1, 2009, and April 30, 2017, were retrospectively reviewed. The center's histological anal cancer data base was questioned in December 2017 to identify all cases.
Results: During a median (interquartile range) follow-up of 19.1 (5.6-40.2) months, 12 (2.9%) anal cancers were diagnosed in patients with a diagnosis of HSIL. Period of time between the first diagnosis of anal lesion and the cancer was 28.8 months (interquartile range = 15.4-65.6), and 11 (92%) of 12 were diagnosed as superficially invasive squamous cell carcinoma or T1N0M0. The rate of progression to anal cancer differed significantly between patients with macroscopic HSIL at diagnosis (5.4%) and patients with microscopic HSIL diagnosed during HRA (0.9%) (p = .01).
Conclusions: Patients with macroscopic histologically proven HSIL at first diagnosis of anal intraepithelial lesion have a significantly higher risk of anal cancer compared with patients with microscopic lesions diagnosed during HRA, but the duration between the first diagnosis of HSIL and cancer does not differ between the 2 groups.