[Deposits of immune complexes in rheumatoid nodule]

The classical histological features of rheumatoid nodules are similar to those of subcutaneous granuloma annulare and necrobiosis lipoidica. The same applied to the DIF images of these lesions. Rheumatoid nodules are more frequent in patients with high rheumatoid factor. Lesions of cutaneous vasculitis are a sign of severity associated with other extra-articular manifestations. Our results are consistent with those of other studies which demonstrated the presence of Ig and/or C deposits in vessels and sometimes at the dermis-epidermis junction. The deposits found in vessels are usually formed of IgM and C3, more rarely of IgG. Those found at the dermis-epidermis junction consist of IgG, IgM and C3. Immune complex deposits in the walls of venules represent the primary mechanism of leukocytoclastic vasculitis. The presence of such deposits on vessels with muscular wall in rheumatoid arthritis suggests an identical pathogenetic mechanism. No alteration of the basal membrane has been noted. The role of deposits at the dermis-epidermis junction has not yet been elucidated.