Idiopathic remitting seronegative symmetrical synovitis with pitting edema syndrome mimicking symptoms of polymyalgia rheumatica: a case report

BACKGROUND: Remitting seronegative symmetrical synovitis with pitting edema is a rare rheumatic condition of the elderly population that is well described but whose mechanisms remain little studied. This syndrome is characterized by symmetrical swelling located mainly on the dorsal part of the hands and the feet. Because of possible heterogeneous clinical presentation, it can easily mimic the onset of other rheumatic diseases or appear associated with them. Here we report a case of a patient who developed remitting seronegative symmetrical synovitis with pitting edema with preexisting shoulder and hip girdle pain associated with progressive fatigue, indicating a possible differential diagnosis of polymyalgia rheumatica. We reviewed and compared classification for remitting seronegative symmetrical synovitis with pitting edema and polymyalgia rheumatica and discussed other differential diagnoses. CASE PRESENTATION: An 84-year-old Caucasian woman presented to our General Medicine Unit with acute onset of symmetrical hands and feet edema, leading to functional limitation due to pain and stiffness. Additionally, she was complaining about neck, shoulder, and pelvic girdle pain present for about 2 months associated with worsening asthenia. Blood tests showed an elevated level of C-reactive protein and erythrocyte sedimentation rate, as well as absence of anti-cyclic citrullinated peptide antibodies and rheumatoid factor. As all criteria of remitting seronegative symmetrical synovitis with pitting edema syndrome were present, the patient was treated with low-dose prednisone, with a rapid and complete resolution of symptoms. She remains asymptomatic without treatment 2 years after the onset of symptoms, without any evident oncologic etiology. CONCLUSIONS: This case is an example of a classic representation of remitting seronegative symmetrical synovitis with pitting edema syndrome with clinical elements suggesting a concomitant existing early stage of polymyalgia rheumatica. These two entities, classified in the group of seronegative arthritis, can coexist (up to 10% of cases), with remitting seronegative symmetrical synovitis with pitting edema appearing as an initial or late manifestation of polymyalgia rheumatica. It is essential to remind that remitting seronegative symmetrical synovitis with pitting edema is associated with a higher risk of cancer (30%). A proper diagnosis allows the clinician to precisely define the appropriate therapy duration to limit its side effects in the elderly and remain aware of the potential risk of underlying malignancy.