KEY POINTS
■ Remitting seronegative symmetrical synovitis with pitting edema (RS3PE) is frequently mistaken for late-onset rheumatoid arthritis or polymyalgia rheumatica (PMR). Misdiagnosis of RS3PE will often result in patients being exposed to more intensive therapy over a longer time.
■ The term synovitis is used in RS3PE because patients present with symmetrical polysynovitis of the joints and fl exor digitorum sheaths associated with pitting edema of the dorsum of the hands and feet. Compared with rheumatoid arthritis, RS3PE is distinguished by its higher incidence in males than females, remitting nature, absence of joint destruction, and negative serology.
■ Both RS3PE and PMR conditions are seronegative, seen at an advanced age, and respond dramatically to low-dose corticosteroids. Both diseases also may manifest with sudden onset of symptoms and an elevated ESR, but PMR is often seen in females whereas RS3PE is more frequently seen in males. The major distinguishing feature is symmetrical pitting edema.
Remitting seronegative symmetrical synovitis with pitting edema (RS3PE) was first described as a subset of acute-onset polyarthritis mainly affecting men in the seventh decade of life and identified as a clinical syndrome in 1985.1 Distinguishing characteristics of RS3PE include symmetrical synovitis that comes on quickly, pitting edema on the back of the hands, lack of rheumatoid factor (RF), and response to a short course of corticosteroids.2
RS3PE is rare and often overlooked by the clinician. The symptoms and signs are frequently mistaken for those of other seronegative polyarthritides of the elderly, most notably late-onset rheumatoid arthritis (LORA) and polymyalgia rheumatica (PMR).3 Misdiagnosis can result in patients being exposed to more intensive therapy over longer periods of time. Thus, despite being rare, RS3PE syndrome, which is highly treatable, should be part of a complete differential diagnosis.
Understanding the differences between RS3PE, LORA, and PMR in terms of patient presentation, diagnostic findings, treatment modalities, and clinical outcomes will better prepare the clinician to make a correct diagnosis.
LIMB AND GIRDLE PAIN WITH EDEMA IN AN ELDERLY PATIENT
An 81-year-old white man presented to a rheumatology practice for evaluation of a recently diagnosed inflammatory arthritis. Symptoms that began several months prior included bilateral shoulder pain and swelling of the wrists, hands, and ankles with new-onset bilateral lower-extremity pitting edema requiring hospitalization. The patient noted no associated headaches, jaw claudication, or vision changes. Personal medical history was negative as was a family history of autoimmune disease. The patient was taking no medications and had no known drug allergies. He was a nonsmoker.
Results of radiologic studies of the patient's hands and wrists were negative for joint erosions, and an MRI of the shoulders was unremarkable. Laboratory studies revealed an elevated C-reactive protein (CRP) level of 42.2 mg/dL (normal reference range, 0-0.5 mg/dL); assays for antinuclear antibody, RF, and anticyclic citrullinated peptide antibody were negative. The patient was found to be anemic, however, and subsequent workup led to a diagnosis of chronic lymphocytic leukemia (CLL). Given the diagnosis, the joint complaints were thought to be paraneoplastic in origin, and the man began treatment for the leukemia.
Six weeks after completing therapy for CLL, the patient was still complaining of significant proximal limb and shoulder-girdle pain in addition to pain and swelling of the wrists, hands, and distal lower extremities. Physical examination revealed 2+ pitting edema of the dorsal aspect of his feet extending to the mid-shin. The hips and shoulders demonstrated decreased range of motion, and mild elbow contractures were noted bilaterally. Also present was synovitis of the wrists and hands. The patient was unable to make a fist with either hand. Swelling allowed him to flex and extend his ankles only minimally, and metatarsophalangeal squeeze elicited tenderness.
The differential diagnosis included RS3PE syndrome, paraneoplastic phenomenon, LORA, and PMR, as well as temporal arteritis, ankylosing spondylitis, the spondyloarthropathies, and polyarteritis nodosa.
The patient was started on prednisone 5 mg three times a day for 2 weeks to be followed by 5 mg twice a day. Three weeks later, his symptoms had improved significantly. On physical examination, the synovitis of the wrist and hands had completely resolved, and the edema in the lower extremities had cleared. Laboratory studies revealed a CRP of 0.7 mg/dL and an ESR of 15 mm/h (normal range in patients older than 50 years, 0-20 mm/h in men and 0-30 mm/h in women). Following the completion of 12 months of low-dose corticosteroids, the patient was without recurrence.