Primary bone lymphoma: radiographic-MR imaging correlation.

Primary bone lymphoma is an uncommon malignancy that accounts for less than 5% of all primary bone tumors. The radiographic appearances of primary bone lymphoma are variable, and, because the lesion can appear near normal on plain radiographs, a second modality such as bone scintigraphy or magnetic resonance (MR) imaging should be used. Despite this variability, the presence of a solitary, permeative, metadiaphyseal lesion with a layered periosteal reaction on plain radiographs and a soft-tissue mass on MR images, especially in a patient older than 30 years, is highly suggestive of lymphoma. The case for a diagnosis of primary bone lymphoma is further strengthened if the soft-tissue mass and marrow changes are associated with surprisingly little cortical destruction. Primary bone lymphoma has a better prognosis than many other malignant bone tumors; therefore, early identification allows for appropriate treatment. MR imaging not only permits early identification but also depicts the extent of soft-tissue involvement and can be used to assess the outcome of treatment.