Primary Lymphoma of the Pelvis: A Case Report.

Introduction: Primary lymphoma of the bone (PLB) is uncommon clinical entity with the vast majority of the cases are non-Hodgkin's lymphoma. Diffuse large B-cell lymphoma (DLBCL) is the most common subtype of PLB.

Case Report: We report a case of 60-year-old female presented with pain in the right hip that persisted for 2 months. Plain X-ray, computed tomography, and magnetic resonance imaging of the right hip showed a lytic lesion involving the right acetabulum and adjoining iliac bone with extraosseous mass. The histopathological and immunohistochemical examination confirmed a diagnosis of DLBCL. Treatment with cyclophosphamide, epirubicin, vincristine, and prednisone plus rituximabestablished a complete response (CR) with remodeling of the acetabulum. At the last follow-up, the patient had the ability to walk without any support which obviates the need of primary surgical interference for the tumor.

Conclusion: The PLB must be considered in the differential diagnosis of lytic lesions involving the pelvic bones in older adults, especially when accompanied by extraosseous soft tissue mass. Our patient of PLB showed goodremodeling of the acetabular area after CR to chemotherapy without primary surgical interference for the tumor with the limitation of weight-bearing during chemotherapy treatment to prevent fracture.