PRIMARY LYMPHOMA OF BONE - CORRELATION OF MAGNETIC-RESONANCE-IMAGING FEATURES WITH CYTOKINE PRODUCTION BY TUMOR-CELLS

Background. Primary lymphoma of bone is a rare, aggressive neoplasm th at can present with a large, soft-tissue mass despite minimal evidence of cortical destruction on plain radiographs. Methods. High resolutio n magnetic resonance imaging (MRI) examinations of four patients with primary lymphoma of bone were reviewed retrospectively, and in each ca se intramedullary tumors demonstrated ''penetrating channels'' extendi ng through the cortex. The MRI studies were correlated with the histop athologic assessment of the tumor for each patient. Immunohistochemist ry was performed for immunophenotyping and for cytokine expression by tumor cells. The cytokines that were investigated were interleukin-1, interleukin-6, and tumor necrosis factor-alpha, molecules known to reg ulate osteoclastic activity. Results. The linear cortical foci noted o n MRI correlated with the histopathologic findings of tumor-associated cutting cones, in proximity to osteoclastic bone resorption. Immunohi stochemical stains showed a B-cell phenotype for each tumor and positi ve immunoreactivity in tumor cells for cytokine mediators that stimula te osteoclastic activation. Conclusions. These findings indicate that the tumor cells in these cases produce soluble cytokine mediators that may regulate extensive osteoclastic activity. In primary lymphoma of bone, tumor activation of osteoclastic resorption, with production of tumor tunnels through the cortex, may represent one of the mechanisms by which lymphoma escapes the intramedullary space and forms large, so ft-tissue masses without extensive cortical destruction.