[Rhizomelic pseudopolyarthritis: update].

Abstract

PURPOSE: Update of recent works on polymyalgia rheumatica (PMR). CURRENT KNOWLEDGE ANS KEY POINTS: In polymyalgia rheumatica (PMR) unassociated with giant cell arteritis (GCA) (twice as frequent as GCA without PMR) several recent works demonstrated by MRI or echography that synovitis and/or subacromial bursitis accounted for most of the painful shoulders and could be relieved by steroid injections. Peripheral synovitis can also occur in 10-20% of PMR, and lead to consideration of other diagnoses, mostly RA or the RS3PE syndromes for those cases of PMR with peripheral edema. PMR with asymmetrical onset are often difficult to diagnose early, and the classification criteria for PMR are not widely accepted. When clinical signs suggestive of GCA are lacking, temporal biopsy is positive in only 1 to 5% of PMR cases. Several studies on PMR with so-called 'normal' ESR (below 30 mm, first hour) have cast doubts on the value of this biological sign (although 'normal ESR' should only stand for values below 11 mm). Hence it would be worthwhile to study whether CRP and even SAA deserve to be added to future sets of criteria for PMR. A defect in hypothalamic axis response is often noticed and could play a part in PMR pathogenesis, thus explaining why PMR is quite exclusively noticed after ages 50 or 60. Two-thirds of patients can stop prednisone within 2 years after the onset of treatment. The lack of a prompt response within the first days should suggest differential diagnoses, including some myelodysplastic disorders. FUTURE PROSPECTS AND PROJECTS: The search for genetic factors common or specific to PMR and GCA could enhance our understanding of these overlapping syndromes. Studies of the transcriptosomes of lymphocytes infiltrating the target tissues (arterial wall in GCA, synovium in PMR) might also prove informative. Controlled studies of new biological treatments like cytokine inhibitors (anti-TNF-alpha, anti-interferon gamma) could demonstrate a clear sparing effect in steroids, a goal not yet achieved by the use of current DMARDs, including MTX.