PRIMARY MUSCLE LYMPHOMA - CLINICAL AND IMAGING FINDINGS

PURPOSE: To assess the clinical and imaging findings in primary muscle lymphoma. MATERIALS AND METHODS: Seven patients with biopsy-proved pr imary muscle lymphoma without evidence of systemic disease underwent i maging with plain radiography or computed tomography (CT) and magnetic resonance (MR) imaging. Four underwent bone scintigraphy, and two und erwent gallium scintigraphy and fluorine-18 fluorodeoxyglucose (FDG) p ositron emission tomography (PET) before and after therapy. RESULTS: P lain radiographs at initial examination (n = 5) showed no bone abnorma lities. Soft-tissue masses and bone marrow involvement showed isoatten uation at CT (n = 3), but at MR imaging (n = 7), all masses demonstrat ed increased signal intensity on T2-weighted images that involved mult iple muscle compartments and typically spanned a long segment of the e xtremity. Adjacent bone disease was less extensive than muscle disease , and, in most cases, subcutaneous stranding or extension was observed adjacent to the masses. Good size correlation was observed between fi ndings at MR imaging, gallium scintigraphy, and FDG PET. Two patients developed recurrent multifocal muscle lymphoma several years after ini tial examination. CONCLUSION: The presence of an extensive soft-tissue mass with infiltration of adjacent subcutaneous fat and minimal or no extension into the bone marrow cavity at MR imaging and normal plain radiographic findings may suggest primary muscle lymphoma.