An aetiology for fistula in ano.

Four cases of superficial peri-anal fistula occurring in early infancy are described. They were all successfully treated by complete excision of the fistula. Histological examination of the excised fistulae revealed a mixture of columnar, transitional and stratified squamous epithelium lining the tracts in three cases and non-specific connective tissue in the fourth. It is postulated that the presence of these inappropriate types of epithelium (columnar and transitional) along the length of the fistulous tract is evidence of a congenital origin for peri-anal fistulae presenting in the first few months of life.