Rheumatoid Arthritis–Associated Pleural Effusion in an Elderly Female With Multimorbidity: A Case Report and Diagnostic Challenge

ABSTRACT We report the case of a 71‐year‐old woman with a background of stage 4 chronic kidney disease (CKD), gout, and COPD, who presented with right‐sided pleuritic chest pain, dry cough, dyspnoea, chronic joint pains, and systemic symptoms. Clinical evaluation revealed a moderate right pleural effusion, confirmed by clinical imaging. Subsequent investigations and autoimmune serologies led to a new diagnosis of rheumatoid arthritis (RA), with RA pleural effusion as the presenting extra‐articular manifestation. Treatment with prednisolone (10 mg twice daily) and methotrexate (5 mg weekly, adjusted for renal impairment) resulted in rapid symptom resolution and radiographic improvement within 72 h, with near‐complete effusion resolution by day 7. This case highlights the rarity of pleural effusion as the initial RA presentation, particularly in elderly females with multi‐morbidity, and underscores the importance of considering autoimmune aetiologies in unexplained exudative effusions to facilitate early diagnosis and prevent complications such as pleural fibrosis.