Tender Cystic Structure on the Back in an Infant.

A 1-year-old Hispanic boy with multiple congenital anomalies including a double-outlet right ventricle, significant scoliosis, kyphosis, and multiple hemivertebrae and hemilamina presented with recurrent febrile episodes. He was found to have Staphylococcus epidermidis meningitis, which persisted despite medical management. On physical examination, a 1×1-cm, tender, erythematous cystic structure with a purulent focus was discovered on the upper portion of his back (Figure 1). His mother noted that the structure was not present at birth, but there was a small red area at the time of delivery that had slowly developed into the lesion shown. T2-weighted sagittal magnetic resonance imaging showed a 4-mm sinus connection from the superficial cystic structure (white arrow) to another 2.4×1.5-cm cystic structure (black arrow) at the level of the hemivertebrae (Figure 2).