Remitting seronegative symmetrical synovitis with pitting edema (RS3PE) syndrome in Nagano, Japan: clinical, radiological, and cytokine studies of 13 patients.

Objective Remitting seronegative symmetrical synovitis with pitting edema (RS 3 PE) has so far been reported almost exclusively from the USA and Europe. We carried out this study to define the clinical characteristics of this syndrome in Japanese patients. Methods Prospectively, we identified 13 Japanese patients with RS 3 PE (5 men and 8 women, age 72.7 ± 11.8 years (mean ± SD)) without underlying neoplasm. Their clinical features were summarized, pertinent laboratory data including serum/synovial interleukin-6 (IL-6) concentrations were detained, and extensive radiologic studies using magnetic resonance imaging and 67 gallium-citrate ( 67 Ga) whole body scintigram were performed. Results All patients suffered from proximal arthralgia/myalgia in addition to typical distal symptoms of RS 3 PE, and all experienced systemic symptoms such as fever, malaise, and weight loss. In laboratory examinations, anemia and elevated inflammatory markers were often remerrkable. Magnetic resonance imaging showed severe tenosynovitis of the hands. 67 Ga-scintigram revealed radioisotope accumulation in both proximal and distal joints of the extremities. IL-6 activity was markedly elevated both in the serum (mean 82.4 ± 62.1 (SD) pg/ml, normal range 0.157-2.94) and in the synovial fluid (mean 3350 ± 633 (SD) μg/ml). Conclusion Compared with cases reported previously from the USA/Europe, Japanese patients with RS 3 PE are characterized by more prominent systemic symptoms/signs associated with marked inflammatory responses including elevated IL-6 activity. All patients had proximal as well as distal synovitis which could be demonstrated by 67 Ga-scintigram. These clinical features were very similar to those of polymyulgia rheumatica, suggesting that RS 3 PE and polymyalgia rheumatica are closely related disorders which may have a common pathogenesis.