Lateral buttock congenital dermal sinus tract.

A 6-month-old female presented with purulent discharge from a dimple in the right lateral buttock. A subcutaneous abscess was palpated on the right paravertebral region at the L5-S1 level. She had low-grade fever with laboratory findings of leukocytosis and elevation of C-reactive protein levels. Klebsiella and Enterococcus species were cultured from the pus. Computed tomography (CT) clearly showed a tract traversing the subcutaneous tissue and connecting to the abscess. Magnetic resonance (MR) imaging showed no abnormality in the spinal canal. The diagnosis was infected congenital dermal sinus (CDS) in the right buttock. After normalization of body temperature and laboratory findings in response to antibiotic treatment, the dermal sinus tract was surgically removed. Intraoperative findings showed that the tract gradually tapered and ended at the subcutaneous abscess space over the lumbosacral fascia. Histological examination confirmed the lesion was dermal sinus. Although laterally placed CDS in the buttocks is extremely rare with only 5 previous cases reported, lateral CDS should be included in the differential diagnosis of a dimple in the buttocks. CT as well as MR imaging should be performed to evaluate suspected lateral CDS.