summary Lymphoma is a malignant hematopoietic tumor that occurs in three forms: primary lymphoma of bone, multiple bony sites, or bone and soft tissue lymphoma. Patients typically present between ages 35 and 55 with regional pain associated with fever, night sweats, and weight loss. Diagnosis is made with biopsy showing mixed small round blue cell infiltrate (different sizes and shapes) that are CD20 and CD45 positive on immunohistochemical stains. Treatment is usually chemotherapy and radiation. Surgical management is indicated for associated fractures. Epidemiology Incidence 10-35% of non-Hodgkin's lymphoma patients have extranodal disease primary lymphoma of bone is very rare Demographics males > females can occur in all age groups most common in patients aged 35 to 55 Anatomic location bones with persistent red marrow most common sites are pelvis, spine, and ribs other common sites include knee (distal femur and proximal tibia), proximal femur, and shoulder girdle risk factors immunodeficiency (HIV, hepatitis) viral or bacterial infections Etiology primary lymphoma of bone (solitary site) most primary lymphomas of bone are Non-Hodgkin's B-cell lymphomas rather than T-cell variants diagnosed when there is only a single node of disease for six months multiple bony sites (no visceral sites) bone and soft tissue lymphoma Presentation Symptoms pain unrelieved by rest 25% present with a pathologic fracture neurologic symptoms from spinal compression fever, nightsweats, weight loss (B-cell symptoms) Physical Exam inspection warm and swollen large soft tissue masses are common Imaging Radiographs large ill-defined diffuse lytic lesions with a subtle mottled appearance more common in the diaphysis of long bones 25% show cortical thickening "ivory" vertebrae multiple sites of disease is common differential diagnosis metastatic disease multiple myeloma osteomyelitis CT CT of chest, abdomen, and pelvis required for staging MRI extensive marrow involvement with large soft-tissue mass Bone scan intensely positive PET useful to stage and follow the disease Studies Biopsy bone marrow aspiration and biopsy are required for staging Histology diagnosis difficult to make with needle biopsy alone because tissue is often crushed mixed small round blue cell infiltrate (different sizes and shapes) differentiate from other small round blue cell tumors CD99 negative and absent 11:22 chromosomal translocation diffuse infiltration of trabeculae (as opposed to nodular) immunohistochemical stains positive CD20 positive CD45 positive lymphocyte common antigen positive Differentials Differential of Lymphoma Destructive lesion in young patients Malignant lesion in older patient Malignant small cells tumor Treatment is chemotherapy alone Lymphoma o o o o Leukemia o o Osteosarcoma o Ewing's sarcoma o o Eosinophilic granuloma o Osteomyelitis o Desmoplastic fibroma o Metastatic disease o o Myeloma o o Chondrosarcoma o MFH o Secondary sarcoma o Rhabdomyosarcoma o Neuroblastoma o Treatment Nonoperative multi-agent chemotherapy +/- local irradiation indications mainstay of treatment radiation may be added to obtain local control in persistent disease techniques cyclophosphamide, doxorubicin, prednisone and vincristine outcomes chemotherapy alone is effective for most lesions 70% 5-year survival in disseminated disease Operative fracture stabilization indications stabilization of pathologic fractures or prophylactic fracture management Prognosis Primary lymphoma of bone has a better prognosis than secondary involvement of bone in lymphoma