Intravascular or intralymphatic histiocytosis associated with rheumatoid arthritis: A report of 4 cases

Background: Various skin lesions occur in association with rheumatoid arthritis (RA). Observation. We report a distinctive skin lesion observed in 4 patients with RA. All patients had RA for many years and developed asymptomatic, irregularly shaped erythema over the swollen elbow joints and the nearby part of the forearm. Histopathologically, all cases showed massive aggregates mainly composed of histiocytes in markedly dilated vessels in the dermis, accompanied by a dermal infiltrate of lymphocytes, plasma cells, neutrophils, or a combination of these. A total of 9 cases, including ours, showing similar histopathologic findings have been reported in the literature, of which 7 were associated with RA and presented relatively common clinical appearance. Conclusion: In spite of some disagreement as to whether the dilated vessels are blood vessels or lymphatics, it is most likely that these 7 cases belong to the same clinical entity closely associated with RA.