To find out clues to differentiate between
polymyalgia rheumatica (PMR) and other diseases that mimic PMR. We studied Japanese patients with PMR (n = 7),
pseudogout (n = 1), remitting seronegative symmetrical
synovitis with pitting
edema (RS3PE) syndrome (n = 1), and post-infectious
polyarthritis (n = 1). The distribution of
inflammation in patients was evaluated using a
gallium-67 scintigraphy. We measured serum
C-reactive protein (CRP), matrix metalloproteinase-3 (MMP-3), and
vascular endothelial growth factor (
VEGF) in patients before and
after treatment. Further, we compared the
clinical course of PMR with that of other diseases that mimic PMR. Patients with
pseudogout, RS3PE syndrome, post-infectious
polyarthritis manifested similar changes in scintigraphic findings and serum CRP, MMP-3, and
VEGF levels to PMR before the treatment. A significant reduction in serum CRP levels at one week after use of nonsteroidal anti-inflammatory drugs (
NSAIDs) is a good clue to differentiate
pseudogout and post-infectious
polyarthritis from PMR.
Chondrocalcinosis in the radiographs of joints is also effective to differentiate
pseudogout from PMR. A small reduction of CRP levels after
NSAIDs use and promptly ameliorated CRP and symptoms by a low-dose
steroid therapy, which was commonly observed in patients with PMR, were also found in a patient with RS3PE syndrome. Pitting
edema of the back of hands and
gallium uptake in metacarpophalangeal (MCP) joints were useful to differentiate RS3PE syndrome from PMR. In conclusion,
pseudogout, RS3PE syndrome, post-infectious
polyarthritis should be included in the spectrum of diseases mimicking PMR. A promptly decreased serum CRP level by
NSAIDs is a good clue to differentiate
pseudogout and post-infectious
polyarthritis from PMR. Pitting
edema of the back of hands and symmetric
gallium uptake in MCP joints are characteristic for RS3PE syndrome.