paraneoplastic syndrome and pmr | Arthritis Information

Paraneoplastic Syndrome

Inflammatory musculoskeletal conditions may be the presenting feature in the aging population as part of a paraneoplastic picture. Rare reports of polymyalgia rheumatica (described above) and the more common presentation of polymyositis and dermatomyositis associated with malignancy (in some studies, up to 20% of patients are affected with increased frequency with each decade over 60) demand a review from a neoplastic perspective of the older patient who presents with true weakness and pain. With myositis in the older adult, one may find proximal muscle weakness of sudden or insidious onset along with muscle tenderness and, at times, synovitis. Dermatitis, scaling over the knuckles (Gottron's papules), and the purplish colour (heliotrope) of the eyelids may be clinical clues that one is dealing with dermatomyositis. Creatine kinase (CK) and other muscle enzymes will be highly elevated, along with acute phase reactants (e.g., ESR and C-reactive protein). Electromyographic studies of involved muscle, showing characteristic fibrillation and spike potentials, and muscle biopsy of the non-EMG side will confirm clinical suspicion. Neoplasia should be considered with a careful evaluation for pulmonary, gastrointestinal, breast, uterus, and prostate assessment. Lymphoproliferative conditions are less common associations. Neoplasia may be evident immediately or months after onset of myositis. Management consists of corticosteroids (60-80mg/day prednisone, at times with immunosuppressives such as azothioprine or methotrexate) and treatment of the tumour in those with neoplasia. With successful treatment of the neoplastic condition the weakness and pain will markedly diminish, though sometimes recurring if the malignancy returns.^[5]

Hypertrophic osteoarthropathy is another paraneoplastic condition that should be recognized. These patients present with the insidious onset (over weeks or months) of symmetrical synovitis, long bone pain, and clubbing. They may be quite ill with low-grade fever and other constitutional symptoms. The arthritis may simulate rheumatoid arthritis. A bone scan will show the periosteum and involved joints "lighting up." The most common tumour is pulmonary, though other tumours and neoplastic conditions have been reported. Treatment involves anti-inflammatory agents and effective treatment of the tumour, with the symptoms of pain improving with successful treatment (and at times returning if the neoplastic condition recurs).

Other paraneoplastic conditions include carcinomatous polyarthritis (often symmetrical synovitis, but without clubbing or periostitis) and, on rare occasion, vasculitic syndromes (a polyarteritis syndrome with atrial myxoma, for example).^[6]