# Primary Remitting Seronegative Symmetrical Synovitis With Pitting Oedema: A Case Report

## TL;DR

This case report describes a rare rheumatological condition called RS3PE syndrome in a 75-year-old man, highlighting its symptoms, diagnosis, and treatment with corticosteroids.

## Contribution

The paper contributes a detailed case report of RS3PE syndrome, emphasizing its diagnostic challenges and association with paraneoplastic syndromes.

## Key findings

- RS3PE syndrome presented with symmetrical arthritis, oedema, and responded well to corticosteroids.
- The patient showed no evidence of neoplasia despite active screening.
- Recurrence of symptoms led to prolonged corticosteroid therapy for sustained remission.

## Abstract

Remitting seronegative symmetrical synovitis with pitting oedema (RS3PE) syndrome is a rare disease that typically presents in older men and is characterised by bilateral and symmetrical peripheral arthritis, pitting oedema in the dorsal hands and feet, and seronegativity for rheumatoid factor. A notable feature of this syndrome is its excellent response to systemic corticosteroid therapy.

This article presents a case of a 75-year-old White male patient recently diagnosed with bilateral carpal tunnel syndrome. He reported complaints of distal and symmetrical inflammatory polyarthralgia for three months, morning stiffness lasting 10 minutes, bilateral hand muscle weakness, and bilateral oedema in the hands and feet. Upon examination, the patient exhibited pain during the palpation of the bilateral metacarpophalangeal, proximal interphalangeal, and tibiotarsal joints, all of which also exhibited signs of inflammation; similarly, flexor tenosynovitis was identified in both hands. Laboratory tests revealed anaemia, hypoalbuminaemia, and elevated acute phase reactants, with negative autoimmune screening and rheumatoid factor. X-rays showed osteoarthritis with decreased periarticular bone density and no evidence of erosions. The patient underwent active screening for neoplasia, which was not evident.

A diagnosis of RS3PE syndrome was established and the patient initiated systemic corticosteroids, gradually tapered over a year, with a favourable response. However, due to symptom recurrence, corticosteroid therapy was reintroduced and continued for an additional two years, resulting in complete and sustained remission.

With this case report, the authors emphasize a rare clinical entity that often mimics other rheumatological disorders, which must be ruled out during the diagnostic process. A high degree of clinical suspicion is essential for diagnosis, after which active screening for neoplasia is required, since RS3PE frequently occurs as a paraneoplastic syndrome.