Superior mesenteric artery branch pseudoaneurysm rupture mimicking acute pancreatitis in a patient with acute type B aortic dissection: A case report

RATIONALE: Visceral arterial pseudoaneurysms are rare but important vascular entities because of their inclination to cause life-threatening hemorrhage. They were commonly reported to be associated with trauma, infection, inflammatory disease, or occurred as postoperative complication. To date, there has been no published report of a superior mesenteric artery (SMA) branch pseudoaneurysm rupture mimicking acute pancreatitis in a patient with acute type B aortic dissection. PATIENT CONCERNS: The patient's medical history, clinical information, imaging findings including follow-up computed tomography angiography (CTA), and treatment are reported. A 51-year-old male presenting with epigastric pain and fever was found to have an enlarged pancreatic head and obscure fatty space around it on abdominal nonenhanced CT. He has medical history of anaphylactoid purpura and uncontrolled hypertension. His serum lipase and amylase were both within normal limits. Thoracoabdominal CTA following a sudden blood pressure drop attributed to the accurate diagnosis. DIAGNOSES: He was diagnosed with acute type B aortic dissection involving SMA and retroperitoneal hemorrhage secondary to SMA branch pseudoaneurysm rupture. INTERVENTIONS: The patient was successfully treated by thoracic endovascular aortic repair without additional branch intervention. OUTCOMES: Follow-up CTA at 3 months later demonstrated that the endoprothesis is well positioned with no endoleaks, and SMA branch pseudoaneurysm disappeared. LESSONS: We report a rare and complicated case presenting with SMA branch pseudoaneurysm rupture and acute type B aortic dissection. CTA is vital in the diagnosis of such vessel pathology. We must inspect carefully to ensure that no small lesions are missed.