General Information

• Primary lymphoma of bone is defined as lymphoma arising within the medullary cavity of a bone in the absence of lymph node or organ involvement for at least 6 months after diagnosis
• Primary lymphoma of bone is rare (3% of primary bone tumors) and most lymphomas that involve bone are metastatic from lymph node. If a lymphoma of bone is diagnosed one must look for another site.
• Most primary lymphomas of bone are Non Hodgkin's, large cell lymphomas
• In U.S. majority are B-cell proliferations
• Must rule out presence of extraskeletal disease
• May be misdiagnosed as chronic osteomyelitis

Clinical Presentation

Signs/Symptoms:

• Localized dull or aching pain
• May have palpable mass or swelling
• Usually no general symptoms and appear healthy
• Pathological fractures in 25% of cases
• Prevalence: Male predilection (1.5:1)

Age:

• Broad age range
• Most occur after second decade with 50% occurring above 40 years
• Rare in children

Sites:

• Any bone can be involved
• Lower extremities involved most often especially femur and pelvis
• More common in appendicular than axial skeleton (opposite of metastatic lymphoma)

Radiographic Presentation

• Permeative or moth eaten bone destruction (55%)
• Geographic (11%); Blow out (1%); Blastic (2%); Normal XR (5%)
• Metadiaphysis (75%)
• Periosteal reaction—may look benign
• Interrupted or solid single layer (66%)
• Onion Skin 10%
• Sunburst 2%
• Soft tissue mass— by CT (80%); by MRI (100%)
• Pathologic Fracture (22%)
• Sequestra (16%)
• Cross Joint (5%)
• Diff Dx:
• Metastatic Lymphoma
• Ewings
• Neuroblastoma
• Rhabdomyosarcoma
• Osteomyelitis
• Eosinophilic Granuloma

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Gross Pathology

• Diffuse infiltrative growth pattern with soft tissue extension
• Intraosseous component
• Mixture of bone spicules and marrow fat as lesion permeates through the medullary canal and has an indistinct margin
• Extraosseous tissue
• Tan or white, resembles lymphomatous lymph nodes
• Areas of necrosis, hemorrhage, and cystic degeneration are present

Microscopic Pathology

• Diffuse growth pattern
• Mixture of small lymphocytic cells and larger histiocytic components (Large Malignant B Cells in most cases)
• Cells and no matrix
• Nuclei
• Vary in shape and size
• Grooved vesicular nuclei
• Prominant nucleoli
• Cytoplasmic glycogen is absent
• Complex reticulin framework
• Prominent fibroblastic component
• CD5 and Leukocyte Common Antigen Positive
• CD3+ and CD45+ for B Cell Lymphoma; CD3+ for Rare T-Cell

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Differential Diagnosis

• Ewing Sarcoma
• Chronic Osteomyelitis
• Leukemia

Treatment

• Chemotherapy and radiation
• If truly an isolated primary lymphoma of bone, limb sparing surgery may be considered instead of or in conjunction with radiation
• Surgical resections to treat residual or recurrent tumors after radiation
• Amputation only recommended when lesions are unresponsive to radiation or recur and are not amenable to limb sparing surgery for various reasons

Prognosis

Patients with:

• Monostotic disease & no soft tissue involvement
• 58% 5-year and 53% 10-year survival

• Multifocal bony disease
• 42% 5 year and 35% 10 year survival

• Osseous lymphoma with lymph node involvement
• 22% 5-year and 12% 10-year survival

• Chemotherapy increases survival rates (88% disease free survival at 7 years) of patients with primary lymphoma of bone
• Has best prognosis of all osseous malignancies except for low grade intraosseous and parosteal osteosarcoma
• Possible better prognosis for lymphomas with cleaved nuclei as compared to noncleaved, immunoblastic or pleomorphic variants