Abstract
Distal extremity swelling with pitting edema in psoriatic arthritis (PsA) is a rare rheumatological condition, whose management presents a challenge. The aim of the present study was to identify the clinical characteristics of, and formulate a standardized management strategy for, patients with distal extremity swelling with pitting edema in PsA. The medical records of consecutive patients with PsA, with or without distal extremity swelling with pitting edema, were systematically analyzed over a ~10-year period (between September 2008 and September 2018) in a single center and a comprehensive review (pathogenic mechanisms, clinical manifestations, and treatments) was undertaken. A total of 167 patients with PsA were evaluated, and distal extremity swelling with pitting edema was recorded in 16 of these patients. In three of the 16 patients, distal extremity swelling with pitting edema occurred as the first, isolated manifestation of PsA. The upper and lower extremities were affected, predominantly asymmetrically. Female patients with PsA were more likely to be affected with pitting edema and the blood test results revealed that the patients with PsA and pitting edema also presented with a significantly higher erythrocyte sedimentation rate and concentration of C-reactive protein. The onset of pitting edema was associated with the activity of the disease. Lymphoscintigraphy and magnetic resonance imaging (MRI) scans revealed that edema might have resulted from inflammation of the tenosynovial structures. Furthermore, treatment with tumor necrosis factor-α inhibitor (TNFi) elicited improvements in patients with pitting edema that were not responsive to conventional synthetic disease-modifying antirheumatic drug therapy. In conclusion, distal extremity swelling with pitting edema, also termed atypical remitting seronegative symmetrical synovitis with pitting edema (RS3PE) syndrome, may represent the initial isolated manifestation of PsA. The atypical RS3PE syndrome in PsA was attributable to inflammation of the tenosynovial structures, and TNFi may serve as a potential treatment.