Lymphoproliferative disorders

1. Leukemia. Leukemic cells may directly infiltrate articular tissues. Poly-arthritis occurs more often with hematologic malignancies than with solid neoplasms. In childhood, the metaphyseal portion of bones is occupied by red marrow. Acute lymphocytic leukemia can present as a migratory or symmetric polyarthritis by infiltrating the periosteum, joint capsule, or metaphysis. It may even mimic rheumatic fever or juvenile rheumatoid arthritis (JRA). The ankle or knee is usually involved. Characteristically, the joint pain is quite severe and disproportionate to any physical findings. The erythrocyte sedimentation rate may be normal. Articular manifestations may develop before the appearance of leukemic cells in the peripheral blood. An elevated serum lactate dehydrogenase or mild leukopenia may help distinguish children with malignant neoplasms who present with musculoskeletal complaints from those who ultimately have JRA. In some cases, immunocytologic analysis can identify leukemic cells in synovial fluid.

2. Vasculitis seen in leukemia is usually limited to cutaneous involvement (except for hairy-cell leukemia). Recurrent leukemic infiltrations into muscles may mimic localized, tender swelling of polyarteritis. Hairy-cell leukemia has been associated with polyarteritis nodosa. Rheumatic manifestations can precede or follow the clinical onset of leukemic symptoms and diagnosis. Rarely, temporal arteritis and polyarthritis, including rheumatoid arthritis (RA) and adult Still's disease, occur. Pathogenesis involves either leukemic infiltration or immune-driven inflammation.

3. Lymphoma. Monarticular or polyarticular symptoms may be related to lymphomatous involvement of juxtaarticular bone. Both Hodgkin's and non-Hodgkin's lymphoma may present with musculoskeletal symptoms. This is attributed to either induction of a synovial reaction by adjacent osseous lymphoma or direct invasion of the joint capsule or synovium. In patients with T-cell lymphomas, a chronic polyarthritis may also develop.

Vasculitis associated with lymphoma is usually limited to cutaneous involvement, presumably on an immune basis. In rare patients with intravascular lymphoma, multiorgan involvement may mimic vasculitis and symmetric polyarthritis.

4. Angioimmunoblastic lymphadenopathy can be associated with rash, polyarthritis, polyclonal hypergammaglobulinemia, and Coombs'-positive hemolytic anemia. This condition may mimic systemic lupus erythematosus (SLE).

5. Myelodysplastic disorders have also been associated with a variety of musculoskeletal symptoms and signs, including polyarthritis, lupuslike conditions, polychondritis, vasculitis, and erythromelalgia.

6. Gout, secondary to rapid cell turnover or tumor lysis, is seen mainly in leukemias and lymphomas. Institution of allopurinol helps prevent this complication. The dosage of azathioprine and 6-mercaptopurine must be reduced if the patient receives concomitant allopurinol therapy.

D. Paraproteinemias. Amyloid arthropathy attributed to deposition of AL protein is associated with dysproteinemias, such as multiple myeloma. It occurs in up to 5% of myeloma patients and is more common in men and those with l light chains. This arthropathy can mimic RA and is associated with carpal tunnel syndrome, shoulder pad sign, and nodules. Erosions are rarely noted. Additional clinical clues that warrant consideration of amyloidosis are hepatosplenomegaly, congestive heart failure, macroglossia, pinch purpura, raccoon eyes, and nephrosis. Biopsy sites to establish a tissue diagnosis include abdominal fat, rectum, synovium, and bone marrow. (see Chapter 51, section I.)

E. POEMS syndrome (plasma cell dyscrasia with polyneuropathy, organomegaly, endocrinopathy, monoclonal protein, and skin changes) can mimic a systemic, multiorgan rheumatic disorder. The skin changes are similar to those of scleroderma.

Raynaud's syndrome, digital ischemic necrosis, and vasculitis may occur in patients with dysproteinemias.

Tendon xanthomas, typically seen in familial hypercholesterolemia, have been reported with near-normal lipid levels in patients with dysproteinemias such as multiple myeloma and monoclonal gammopathy of unknown significance (MGUS). F. Metastatic carcinomatous arthritis associated with solid neoplasms. Metastatic deposits of solid neoplasms in bone, synovium, or periarticular tissue can masquerade as monarthritis or polyarthritis. This is a rare occurrence. The synovial membrane can either react nonspecifically to adjacent malignant deposits or, less commonly, contain tumor itself. In general, the incidence of appendicular bone metastases lessens with increasing distance from the axial skeleton. Phalangeal metastases are usually caused by bronchogenic or gastrointestinal carcinomas and can mimic gout, osteomyelitis, osteoarthritis, or even RA. Metastatic breast carcinoma is the most common cause of metastatic carcinomatous arthritis in women. Joint effusions can rarely be associated with solid tumors in the absence of radiographically apparent periarticular osseous metastasis. In such cases, synovial fluid cytology or synovial tissue biopsy specimens may be positive for tumor cells in two-thirds of patients. In patients with unresponsive or progressive unilateral sacroiliitis, additional imaging and biopsy should be considered to detect metastatic carcinoma.

In children, neuroblastoma should be considered as a cause of metastatic carcinomatous arthritis. In most instances, the primary neoplasm is evident. If the tumor is occult, tomography, bone scan, or biopsy becomes necessary for accurate diagnosis. In general, therapy is directed toward the underlying neoplasm.

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