Epiphyseal presentation of non-Hodgkin's lymphoma of bone in two pediatric patients--one with primary lymphoma of bone.

We report two children with lymphoma of bone centered in the distal femoral epiphysis who presented with knee pain. Radiographs, magnetic resonance imaging (MRI) and computed tomography (CT) were performed on both patients prior to biopsy. Following biopsy, both patients had fluorodeoxyglucose ((18) F-FDG) positron emission tomography/CT (PET/CT) and whole-body technetium-99m (Tc-99m) scintigraphy performed for staging. One patient met the criteria for primary lymphoma of bone. One patient did not meet the criteria for primary lymphoma of bone because of PET uptake in a popliteal, external iliac and possibly lower abdominal node. Both patients responded well to chemotherapy and are disease free more than 7 years after diagnosis. While an epiphyseal presentation of lymphoma of bone is rare, the efficacy of treatment and the compromised outcome associated with diffuse spread of the disease make early recognition by clinicians important. We present these two cases to increase awareness of the disease and to have clinicians consider it in the differential diagnosis of adolescent epiphyseal lesions.