Pathological fracture of the femur without surgical fixation in primary bone diffuse large B-cell lymphoma (DLBCL): A rare case with full recovery

Primary bone lymphoma (PBL) is a rare extranodal non-Hodgkin lymphoma that accounts for less than 5% of primary bone tumors and 1–3% of non-Hodgkin lymphomas. Diffuse large B-cell lymphoma (DLBCL) is the most common histologic subtype. Pathological fractures are an uncommon initial presentation. We report the case of a 24-year-old male of North African origin, with no prior medical history, presenting with acute pain and functional limitation of the left lower limb. Imaging revealed a bifocal pathological fracture of the distal femur with osteolytic changes and cortical destruction. MRI demonstrated bone marrow replacement, cortical disruption at two levels, and periosteal and muscle involvement. Histological and immunohistochemical analysis confirmed the diagnosis of PBL-DLBCL. No extraosseous disease was detected. Although surgical stabilization was proposed, the patient refused the operation, and a circular cast was applied. The patient subsequently underwent radiotherapy (30 Gy in 10 fractions) and six cycles of R-CHOP chemotherapy, achieving complete fracture healing and full functional recovery after four months. This case illustrates a rare presentation of PBL-DLBCL complicated by a pathological fracture, successfully managed without surgical fixation following the patient's refusal of surgery. The favorable clinical and functional outcome suggests that surgical intervention should be considered on a case-by-case basis, taking into account fracture risk, clinical stability, and the need to avoid delays in systemic therapy. Further studies are required to establish clear guidelines for managing pathological fractures in PBL.