Primary Bone Lymphoma in Adults: A Report of Two Cases and Review of the Literature Highlighting the Role of Radiotherapy.

Primary bone lymphoma (PBL) is a rare extranodal hematologic malignancy that can pose significant diagnostic challenges. Patients commonly present with localized pain, swelling, pathological fracture, or neurological deficits, and the disease may mimic infection, degenerative conditions, trauma, or metastatic carcinoma. Lesions can arise in any skeletal site, underscoring the importance of interdisciplinary awareness among orthopedics, neurosurgery, dentistry, and oncology. Histologically, diffuse large B-cell lymphoma is the most frequently encountered subtype, with certain molecular features carrying important prognostic implications. Accurate diagnosis depends on adequate tissue sampling, immunophenotyping, and staging with positron emission tomography/computed tomography, and repeat or open biopsy may be required in select cases. Management is typically optimized with combined chemo-immunotherapy, most commonly rituximab-based regimens, with or without consolidative radiotherapy to improve local control and symptom relief. Surgical intervention is generally reserved for diagnostic purposes or skeletal stabilization. We report two cases of elderly patients, one Middle Eastern male and one White female, with stage IE PBL involving the sacrum and iliac crest, respectively. Both patients were treated with systemic therapy followed by salvage involved-site radiotherapy, achieving durable local disease control and symptom resolution. Early recognition of PBL enables effective multimodal treatment and favorable clinical outcomes. This case series highlights the diagnostic complexity of PBL, emphasizes the role of radiotherapy in management, and underscores the need for standardized treatment approaches to optimize care for this rare lymphoma subtype.