Osteonecrosis during the treatment of childhood acute lymphoblastic leukemia: a prospective MRI study.

BACKGROUND: Since the survival rates of childhood leukemia have improved, attention is increasingly focused on the long-term effects of the treatment. Osteonecrosis may complicate the treatment of acute lymphoblastic leukemia (ALL). To have more information about the natural history and clinical course of the development of osteonecrosis, a prospective MRI study was designed. PROCEDURE: The development of osteonecrosis was studied prospectively in 24 consecutive children with ALL who underwent T1-weighted magnetic resonance imaging (MRI) scanning of the lower extremities at the beginning of, during, and at the cessation of the chemotherapy. The general bone marrow signal intensity was assessed together with focal lesions. Circumscribed lesions with a rim of low signal intensity were considered typical of osteonecrosis.
RESULTS: Nine of the 24 patients (rate 38%) developed osteonecrosis during the treatment. Six of them were asymptomatic. MRI lesions regressed in size in six patients, and in three patients the MRI finding returned to normal. No operative treatment was needed. The osteonecroses appeared immediately or within a few months after the delayed intensification phase with intensive dexamethasone medication.
CONCLUSIONS: Corticosteroids have been considered to be the main pathogenetic factor in the development of osteonecrosis in children with malignancies, which was also suggested by our findings. However, there is a lack of systematic prospective studies concerning the natural history and long-term follow-up observations of the prognosis of osteonecrosis, especially in pediatric patients. Based on our results, the lesions are often asymptomatic and cause no disability, and spontaneous improvement or even resolution may occur.