Serum amyloid A as a potent therapeutic marker in a refractory patient with polymyalgia rheumatica.

We report a patient with polymyalgia rheumatica (PMR) who showed a relapse soon after tapering of oral prednisolone. C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) were quickly normalized after the re-increase in oral prednisolone, and muscle pain and stiffness gradually improved in parallel with a decrease in serum amyloid A (SAA). Flow cytometry simultaneously demonstrated an increase in CD8+CD25+ cells and a decrease in CD4+CD25+ cells and CD4+CD45RA+ cells. When clinical symptoms remain with negative results for CRP and ESR even after the start of corticosteroid treatment, SAA might be a potent therapeutic marker for disease activity in PMR.