A Rare Case of Pericardial Involvement in Pseudomyxoma Peritonei.

Pseudomyxoma peritonei (PMP) is an uncommon clinical entity characterised by the progressive accumulation of mucinous ascites within the peritoneal cavity. We describe the case of a 59-year-old man with recurrent PMP secondary to an appendiceal mucinous neoplasm, who presented with acute chest pain and dyspnoea. Investigations revealed transient constrictive pericarditis with mild pericardial effusion and associated precardiac lymphadenopathy. Management with anti-inflammatory therapy led to clinical and echocardiographic resolution of pericardial inflammation. This case highlights an association between PMP and pericardial involvement, emphasising the importance of early echocardiographic evaluation in PMP patients presenting with chest pain. Recognising this rare association may guide timely and appropriate management, preventing the development of potentially life-threatening cardiac tamponade.