The rheumatoid papule is a recently described skin manifestation of rheumatoid arthritis.
Rheumatoid papules from four patients with classic rheumatoid arthritis were examined to determine the origin of this palisading granulomatous reaction.
Immunofluorescence and electron microscopic studies were performed on biopsy specimens of rheumatoid papules.
Leukocytoclastic vasculitis with collagen alteration and lymphohistiocytic infiltration were observed. The immunofluorescence study revealed deposits of immunoglobulins and complement in the vessel walls and in the area of collagen alteration. Electron microscopy revealed epithelioid cell-like histiocytes among altered collagen fibers. These cells contained abundant lysosomes and were connected to neighboring cells by well-developed intricate processes.
Vasculitis is important in the pathogenesis of rheumatoid papules. In patients with rheumatoid papules, systemic evaluation should be performed because these are a manifestation of rheumatoid vasculitis.