Nodules in Rheumatoid Arthritis

Abstract

Rheumatoid nodules (RN) are common in rheumatoid arthritis (RA) patients. Approximately one-quarter of RA patients will have them. They are one of seven diagnostic criteria for RA. They typically appear over bony prominences and joints such as the elbows and Achilles tendon. They are firm, subcutaneous, flesh-colored nodules that may grow to 1 cm in size or larger. They are usually non-tender. They are most often diagnosed clinically on exam and a biopsy is not necessary. They may occur in unusual locations such as the lungs and CNS. The differential diagnosis for RN includes acute rheumatic fever nodules, calcinosis, tophi, xanthomas, subcutaneous granuloma annulare, Gottron’s papules of dermatomyositis, and multicentric reticulohistiocytosis. Some SLE patients will develop RN. Less commonly, smaller, more papular lesions in a similar distribution in SLE and RA patient may have palisaded neutrophilic and granulomatous dermatitis (PNGD). Treatment of RN is the same as treatment of RA, but sometimes the RN may fail to respond. When confronted with an atypical nodule, a biopsy may be helpful. A biopsy of rheumatoid nodules demonstrates a palisaded granulomatous pattern with fibrosis and fibrin in the centers of palisaded zones. Some nodules in patients with rheumatoid arthritis and other autoimmune disease may display features of palisaded neutrophilic and granulomatous dermatitis.