Subcutaneous fistula in infancy: a different diagnosis of a perianal discharging nodule

Fistula-in-ano (FIA) is an abnormal communication between the anal canal and the perianal skin with an external exit hole draining spontaneously. In FIA the fistulous tract starts from a deep acute purulent inflammation of the anal region, usually an abscess. Perianal abscess (PA) generally arises from the acute infection of a small gland just inside the anus due to the entry of bacteria or foreign material in the gland. In the first year of life PA and FIA are associated and, in contrast to other age groups, in infants they seem to have mainly a malformative origin, without the presence of an underlying concomitant disease. PA is normally the forerunner sign of FIA while it is exceptional to find FIA alone. We present here the case of a 8-month-old boy with a superficial subcutaneous fistula-in-ano unpreceded by PA. Pathogenesis and management are reported as well as a review of the literature.