RECURRENT PLEUROPERICARDITIS ASSOCIATED WITH MESALAZINE THERAPY MASKED BY STEROID USE

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Demiröz H., ERUZUN H., Çakmak H. D., Ulusoy A. C., Ketenci Y. B., Akca M., ...More

European Journal of Case Reports in Internal Medicine, vol.13, no.5, 2026 (Scopus)

Abstract

Introduction: Mesalazine is a cornerstone therapy for ulcerative colitis (UC). Although generally safe, it can cause rare but life-threatening cardiopulmonary complications such as pleuropericarditis. Case description: We report on a patient with a UC flare who presented with dyspnoea, where concurrent pericardial and pleural effusions were detected. The inflammatory response was likely suppressed by concomitant corticosteroid therapy, which masked the clinical manifestations of mesalazine-induced serositis and delayed diagnosis. Two years later, the patient re-presented with recurrent massive pericardial effusion causing tamponade physiology and pleural effusion. Pericardial fluid analysis revealed a haemorrhagic, neutrophil-dominant profile (95% polymorphonuclear leukocyte, mimicking bacterial infection rather than the typically described eosinophilic pattern. Extensive cultures were negative. Following the discontinuation of mesalazine, rapid clinical and radiologic improvement was observed, confirming drug-induced pleuropericarditis. Discussion: This case highlights that mesalazine-associated pleuropericarditis can be obscured by corticosteroids, leading to diagnostic delays. Furthermore, sterile inflammatory reactions to mesalazine can present with atypical neutrophilic features resembling bacterial infection, necessitating a high index of suspicion in inflammatory bowel disease patients presenting with serositis.