Murali Daviluri, MD

A mother, fearing that her 4-year-old son had been abused at his day-care center, rushed him to the emergency department, where an evaluation revealed a platelet count of 1,000/µL. Except for bruises on the boy's face and legs, the physical findings were normal. Bone marrow aspiration showed numerous megakaryocytes and was otherwise normal. The youngster's history included treatment for bronchitis, sinusitis, and conjunctivitis 2 weeks earlier.

Two 7-year-olds show the purpuric rash of the lower body and legs that is typical of Henoch-Schönlein purpura. This disease is a vasculitis that chiefly affects small vessels of the skin, joints, gastrointestinal tract, and kidney.