Abstract
Pseudomyxoma peritonei (PMP) is a rare clinicopathological condition characterised by mucin-producing peritoneal and omental deposits with an estimated incidence of 1-2 cases per million per year. We report a 42-year-old female patient who presented to a tertiary care hospital in Muscat, Oman, in 2023 due to a 7-year history of chronic diarrhoea associated with progressive abdominal distension over the past 2 years. Her assessment was significant for ascites. No neoplastic lesions were found on the upper and lower gastrointestinal scopes. A diagnostic ascitic tapping revealed a free flow of gel-like thick, yellowish fluid. A diagnostic laparoscopy showed a perforated appendicular mass with diffuse peritoneal nodules and mucin ascites. Subsequently, the patient underwent cytoreductive surgery with heated intraperitoneal chemotherapy. On follow-up, the patient's abdominal distension and diarrhoea had resolved. This case reports an unusual presentation of a very rare disorder and highlights the challenge of diagnosing PMP.