The yield of routine histopathology in fistula-in-ano: a retrospective analysis

Abstract Objective Fistulae-in-ano with a specific aetiology such as TB and Crohn’s are usually complex and challenging to treat. This study was aimed to determine the yield of routine histological analysis in fistula-in-ano, in detecting specific aetiology. Histopathology reports of all patients without a previous diagnosis, who underwent surgery for fistulae-in-ano were retrospectively analysed. Results A total of 215 patients [median age:40 years(range:14–73), males = 178(82.8%)] were analysed. The majority(75%,n = 161) were simple fistulae and recurrent(67%,n = 145). Histological evaluation revealed inflamed granulation tissue in 94.9%(n = 204) of patients. Five(2.3%) patients had conclusive evidence of Crohn’s disease and three(1.4%) had tuberculosis. One patient(0.5%) had evidence of adenocarcinoma with mucinous differentiation. Significant proportion of fistula with a specific aetiology were complex fistulae (82%vs.22%,p < 0.001) and associated with abscess/collections (45.5%vs.11.8%, p < 0.001). Age, type of fistula, level of internal opening, recurrence and presence of haemorrhoids were comparable in those with and without a specific aetiology. One patient with Crohn’s and those with TB did not have any associated symptoms to suggest the diagnosis. Routine histopathological analysis in patients presenting with fistula in-ano should be performed as clinical prediction based on the nature of fistula may not be always accurate.