Pseudomyxoma peritonei following fine needle aspiration of a large intraductal papillary mucinous neoplasm: A case report

Pseudomyxoma peritonei (PMP) is a rare disorder characterized by diffuse intraperitoneal mucin accumulation, most often arising from appendiceal or ovarian mucinous neoplasms. Less frequent primary sites include the colon, small bowel, gallbladder, lung, and urachus, and rarely, the pancreas. Pancreas-associated PMP has been reported with mucinous adenocarcinoma and intraductal papillary mucinous neoplasms (IPMN), typically due to spontaneous cyst rupture or iatrogenic spread after resection with positive margins. We report a case of rapid-onset PMP following fine needle aspiration (FNA) of a large IPMN, with findings suggestive of procedural rupture. An 81-year-old woman with atrial fibrillation and asthma underwent imaging after a fall, revealing an 18 cm multilobulated macrocystic mass of the pancreatic body and tail concerning for malignancy. Endoscopic ultrasound-guided FNA was performed which demonstrated no carcinoma. Soon after, she developed progressive abdominal distension and mucinous ascites. Exploratory laparotomy at an outside hospital evacuated 3.5 liters of intraperitoneal mucin without resection. Persistent symptoms prompted referral to our institution, where she underwent debulking with evacuation of 8 liters of mucin, distal pancreatectomy, splenectomy, and cholecystectomy. Her postoperative course was prolonged but stable, and she was discharged to a skilled nursing facility with ongoing outpatient follow-up. This case highlights a rare but significant mechanism of peritoneal dissemination in IPMN. While FNA is commonly used for diagnostic evaluation, instrumentation of large, tension-filled cystic neoplasms may precipitate rupture and subsequent PMP, warranting careful consideration when sampling giant IPMNs.