Histopathological analysis of sixteen subcutaneous rheumatoid nodules

An immunopathological study was carried out on subcutaneous nodules (rheumatoid nodules) biopsied from 16 patients with rheumatoid arthritis. Sixteen rheumatoid nodules were histologically classified into three stages, the 1st stage (acute inflammatory stage, 3 cases), the 2nd stage (granulomatous stage, 10 cases), and the 3rd stage (scar-formed stage, 3 cases). In necrotic or granulation tissue of the nodules in the 3 stages, immunofluorescent analysis using FITC-labeled rabbit anti-human immunoglobulins, beta 1C, and fibrinogen serum gamma-globulins and FITC-labeled aggregated human IgG gave results that were strongly positive in the 1st stage, moderately positive in the 2nd stage, and only slightly positive or almost negative in the 3rd stage. Acute or chronic thrombotic endoarteritis was observed around rheumatoid nodules in 6 out of the 16 cases. Among them, 2 cases of the 1st stage showed acute thrombotic endoarteritis with marked infiltration of neutrophils in the wall, and 2 cases of the 2nd and the 3rd stages respectively showed chronic endoarteritis with organized thrombi.