Musculoskeletal lymphoma: MRI of bone or soft tissue presentations

To assess the MRI findings of musculoskeletal lymphoma primarily presenting clinically as a bone lesion or soft tissue mass.

Magnetic resonance imaging of 23 cases of musculoskeletal lymphoma were retrospectively reviewed. Features assessed included tumour location, morphology, signal intensity (SI) characteristics, cortical destruction, involvement of multiple anatomic compartments, encasement of adjacent neurovascular structures/tendons and subcutaneous oedema.

Osseous lesions were typically poorly defined and hypointense on T1-weighted imaging. T2-weighted SI was usually heterogeneous, with 54% of cases having a 'mosaic' pattern of marrow replacement. Ninety-two per cent of osseous tumours had cortical abnormalities, most commonly a permeative pattern. A periosseous soft tissue cuff was present in 46% of cases while 38% had a more significant extraosseous component. All cases of soft tissue lymphoma were iso-/slightly hyperintense to muscle on T1-weighted images and hyperintense on T2-weighted images. Multicompartment involvement by extraosseous tumour was present in 75% of cases, and 67% had subcutaneous oedema. Eighty-three per cent of soft tissue tumours showed encasement of adjacent structures. Multifocal lymphoma had similar morphology and SI characteristics to single-site lesions. Histopathologically, there were 21 cases of non-Hodgkin's lymphoma and two of Hodgkin's lymphoma.

Magnetic resonance imaging features of primary osseous lymphoma include T2 heterogeneity, a periosseous soft tissue cuff or a more substantial mass, and cortical disruption often disproportionate to the extent of extraosseous tumour. Features characteristic of soft tissue lymphoma include relative homogeneity on T1- and T2-weighted imaging, multicompartment involvement and encasement of neurovascular structures.