Primary bone lymphoma: a radiologic-pathologic series of 72 cases uncovering the diagnostic complexity of a rare and...

Primary bone lymphoma (PBL) is a rare extranodal lymphoma accounting for approximately 7% of malignant primary bone tumors. It typically presents with nonspecific features, frequently resulting in diagnostic delay and inappropriate initial management.

We retrospectively analyzed the characteristics of 72 patients diagnosed with PBL between 1966 and 2025 at a tertiary referral center in Spain.

Diffuse large B-cell lymphoma (DLBCL) was the predominant histological subtype. The most frequent presentations included persistent bone pain, pathological fractures, and palpable masses, often associated with elevated LDH levels or underlying immunosuppressive conditions. Imaging findings were heterogeneous, ranging from permeative lytic patterns to sclerotic lesions, occasionally resembling osteomyelitis or other aggressive neoplasms. MRI proved essential for early detection, accurate assessment of bone marrow infiltration, and soft tissue extension, while CT played a key role in biopsy guidance. FDG PET/CT was critical for staging, restaging, and treatment response evaluation. Diagnostic precision depended heavily on close clinico-radiological-pathological correlation, particularly in cases with atypical or misleading imaging patterns. Most patients were treated with combined chemotherapy and radiotherapy, which was associated with high response rates and favorable survival outcomes.

PBL is an uncommon but potentially curable malignancy. Early diagnosis requires a high index of suspicion and systematic integration of clinical data, laboratory findings, and multimodal imaging. PBL should be systematically considered in patients presenting with aggressive-appearing bone lesions, pathological fractures, or unexplained marrow replacement, especially in the presence of elevated LDH levels or immunosuppression, in order to prevent diagnostic delay and optimize outcomes.