A 14-year-old previously healthy boy presented with a 2-month history of a painless "rash" on his left flank and right thigh. He also complained of intermittent headache, and his parents believed that his personality had changed recently. He had no history of fever, anorexia, weight loss, or trauma. On physical examination, he was an alert and cooperative boy. There was no evidence of papilledema, and results of his neurologic examination were entirely normal. His abdomen was soft, nontender, and without masses or organomegaly. An indurated violaceous lesion measuring 3×8 cm was noted on his right thigh (Fig 1). A similar 5×4-cm lesion was also noted on his left flank.
Laboratory findings were as follows: leukocyte count, 8.6×109/L with 0.50 segmented neutrophilis, 0.45 lymphocytes, and 0.04 monocytes; hematocrit, 0.41; erythrocyte sedimentation rate, 2 mm/h; and prothrombin time and activated partial thromboplastin time, normal. Cerebral spinal fluid had a white blood cell count of 23×106/L with 0.90 polymorphonuclear cells, 0.05 monocytes, and