Late-onset congenital lateral dermal sinus tract.

Cases of laterally located, congenital dermal sinus tracts are extremely rare, with only six having been reported to date. We describe a case of a 14-year-old girl who developed symptoms of this type of sinus tract at an age that was considerably older than is usually reported. At the age of 12 years, the patient exhibited a purulent discharge from a pit on the right buttock. MRI indicated the presence of two tracts running from the right buttock skin to a cystic lesion that had formed on the right ala of the sacral spine. The lesion was surgically resected and successfully reconstructed using a partial iliocostalis lumborum muscle flap, without any functional morbidity. From our experience, such flaps appear to be appropriate treatment choices for lateral congenital dermal sinus tracts that develop late and result in large defects.