Lumbar Artery Pseudoaneurysms Presenting as a Novel Complication of Severe, Necrotizing Pancreatitis.

Splanchnic artery pseudoaneurysms are a known complication of necrotizing pancreatitis. Lumbar artery pseudoaneurysms are rare and usually associated with trauma, renal biopsy, or spinal procedures. We present a rare case of lumbar artery pseudoaneurysms as a complication of necrotizing pancreatitis. A 55-year-old man initially presented with necrotizing biliary pancreatitis complicated by peripancreatic necrotic fluid collections and walled-off necrosis requiring multiple endoscopic ultrasound-guided necrosectomies. Inferoposterior extension of collections to the retroperitoneum caused lumbar artery pseudoaneurysms, leading to hemorrhagic shock from retroperitoneal and intraperitoneal hemorrhages.