Primary bone lymphoma

Primary bone (skeletal/osseous) lymphoma (PBL) is a less common manifestation of lymphoma than secondary involvement from disseminated lymphoma. It is rare, accounting for <5% of bone tumors and <1% of non-Hodgkin lymphoma.

Terminology

PBL is defined as the presence of lymphoma isolated to one bone without distant spread for six months after diagnosis. Multifocal PBL is less common and occurs with lymphoma is confined to two or more bones, again without distant spread for six months ¹.

Epidemiology

PBL can affect any age group, with peak incidence in (50-60) year-olds. It is rare in children <10 years old. There is a slight male predominance (M:F = 1.5:1) ². 

Clinical presentation

Symptoms include localized pain and swelling, B-type symptoms, pathological fractures, and cord compression.

Pathology

Diffuse large B cell lymphoma (DLBCL) is the most common subtype. The bony pelvis and femur are the most common locations ³.

Radiographic features

Plain radiograph

PBL has non-specific features and the affected bone may be normal or affected by lytic, sclerotic or mixed pattern. The most common is a lytic pattern with permeative bone destruction and a wide zone of transition ¹.

MRI

Associated soft tissue masses are common. Bone marrow changes include ²:

• T1: low signal
• T2: high signal

Treatment and prognosis

Five-year survival rate has been reported at ~ 80%, much better than other bone tumors ².

Differential diagnosis

For plain film presentation of permeative bone destruction consider ¹:

• infection
• eosinophilic granuloma
• Ewing sarcoma
• skeletal metastases