Palindromic rheumatism: part of or apart from the spectrum of rheumatoid arthritis.

Palindromic rheumatism (PR), originally described in 1944, is characterized by recurrent episodes of mostly oligoarticular arthritis with peri- and para-articular tissue inflammation, leaving no residual clinical and radiographic changes. It appears that palindromic syndrome is a heterogeneous entity, encompassing other inflammatory conditions at early stages of their evolution, and whose relationship with rheumatoid arthritis (RA) is evident but still unclear. Evolution of up to 50% of these cases into otherwise typical RA, commonly accompanied by the conversion to rheumatoid factor seropositivity, the frequent occurrence of nodules, the reported response to RA treatment, and the observation of familial aggregation of the two conditions suggest that PR is part of the spectrum, or a stage in the evolution of RA. However, justification for the distinct existence of PR comes from reports that identify well-defined and recognizable clinical manifestations such as descriptions of the acute attacks, the frequent peri-articular manifestations, the absence of bone and cartilage destruction even after extended periods of time, and the generally good long-term prognosis. Immunogenetic studies with HLA-DR phenotyping and the absence of female preponderance tend to add additional support for the separate identity of PR.