IL6 and rheumatoid arthritis: Although we have not found studies of cytokine levels in rheumatoid pericardial effusions, there is a case report of high levels of IL-6 in a rheumatoid pericardial effusion and a case of successful treatment of an effusive–constrictive pericarditis secondary to rheumatoid arthritis with an anti-IL-1 agent (anakinra), suggesting a role for these cytokines, in this extraarticular manifestation, as well as in others [132,133].