An 11-month-old black boy presented with a 1-week history of a "knot" in his back. He had been evaluated 1 month before because of a temperature of 40°C and was found to have pneumonia of the left upper lobe that was treated with administration of cefuroxime and a combination of amoxicillin and clavulanate potassium.
He was a well-nourished, 10.9-kg infant with a flexed back who was listless and afebrile. Results of physical examination were remarkable for a 4.5-cm posterior chest mass at the T-10 level. The mass was firm, protruding, tender, nonfluctuant, nonmobile, and without erythema or local heat. The erythrocyte sedimentation rate was 108 mm per hour, and results of an intradermal tuberculin test were 20 mm at 24 hours and 25 mm with central necrosis at 72 hours. A second chest roentgenogram (Fig 1), a lateral roentgenogram of the chest (Fig 2), and a computed tomogram of the