S3207 Spontaneous Fistulization of a Hemorrhagic Pancreatic Pseudocyst Leading to Occult Splenic Artery Bleeding: A Case Report

Introduction: Hemorrhagic necrotizing pancreatitis can lead to complex pseudocyst formation, sometimes complicated by the development of splenic artery pseudoaneurysms. Spontaneous fistulization of such pseudocysts into the gastrointestinal tract is a rare event. This can paradoxically lead to occult but significant bleeding if the fistulization reduces the tamponade effect on an underlying arterial pseudoaneurysm, posing a diagnostic and therapeutic challenge. Case Description/Methods: A 65-year-old woman with a history of biliary pancreatitis (post-cholecystectomy 2019) and alcohol use presented with progressive abdominal pain and weight loss. Initial magnetic resonance imaging and computed tomography angiography revealed hemorrhagic necrotizing pancreatitis with complex collections/hemorrhagic pseudocysts and multiple splenic infarcts, but no active extravasation. The patient was managed conservatively due to the high risk associated with drainage. In February 2025, she presented with severe anemia (hemoglobin 5.2 g/dL) without overt bleeding. Repeat computed tomography showed interval decrease in the pseudocyst size but new gas and air-fluid levels, suggesting superinfection or enteric fistulization. A subsequent computed tomography angiography (CTA) revealed 3 splenic artery pseudoaneurysms (14 mm, 18 mm, 5 mm) within the collection, with signs of recent hemorrhage but no active extravasation. It was hypothesized that spontaneous pseudocyst fistulization had occurred, leading to internal decompression and intermittent, occult bleeding from the pseudoaneurysms. Immediately following this CTA, the patient experienced a pulseless cardiac arrest, was resuscitated, and underwent urgent interventional radiology coil embolization of the splenic artery pseudoaneurysms. She recovered and was discharged with plans for close outpatient follow-up. Discussion: This case illustrates a rare, complex sequence of events where a hemorrhagic pancreatic pseudocyst fistulized spontaneously into the gastrointestinal tract. This fistulization, while contributing to pseudocyst decompression, is thought to have unmasked or exacerbated bleeding from pre-existing splenic artery pseudoaneurysms by reducing the tamponade effect. Diagnostic challenge lay in identifying the source of bleeding in the absence of overt signs. This case underscores the importance of a high index of suspicion for vascular complications in patients with resolving or changing pancreatic collections and anemia, and highlights the critical role of multidisciplinary management, including timely interventional radiology, in such life-threatening scenarios.