Osteonecrosis in an adolescent with non-Hodgkin lymphoma resembling a new metastatic lesion on (18)F-FDG PET/CT.

Osteonecrosis may result from complications in a variety of pediatric diseases and, in the early stages of healing, may be characterized by inflammation and hyperemia. While traditionally assessed by bone scintigraphy, osteonecrosis may also present upon [F-18]2-fluoro-2-deoxyglucose PET/CT. Differentiation of osteonecrosis from metastatic lesions is important to ensure accurate disease staging and to avoid unnecessary imaging and biopsy. Osteonecrosis typically presents at the interface of weight-bearing joints after prolonged chemotherapy with corticosteroid administration, although prevalence is greater in adults than in children. We describe a case of unilateral osteonecrosis in the tibia of an adolescent lymphoma patient, which first presented on FDG-PET/CT imaging after 2 months of combination chemotherapy with corticosteroid administration. This report should aid in recognizing rapid-onset osteonecrosis with atypical sites of involvement in pediatric patients.