MRI-negative, bone scintigram-positive in early osteonecrosis of the knees.

Nontraumatic avascular necrosis (AVN) of bone is a well-reported complication of glucocorticoid therapy for immunologic and malignant disease. We present the case of a 13-year-old girl with no history of trauma who presented with a 5-day history of increasing pain in both knees after cord blood transplantation for acute lymphoblastic leukemia. Plain film and magnetic resonance imaging (MRI) were reported as normal.