A 55-Year-Old Man Presenting with Recurrent Upper Abdominal Pain

IgG4-related autoimmune pancreatitis (IgG4-AIP) is an immune-mediated disease that can present as recurrent acute pancreatitis with biliary involvement. We report a case of a 55-year-old male with recurrent acute pancreatitis and obstructive jaundice of unknown cause. Laboratory tests revealed elevated IgG and IgG4 levels, while imaging showed pancreatic swelling, main pancreatic duct stricture, and distal bile duct stenosis. Endoscopic ultrasound-guided biopsy confirmed IgG4-positive plasma cell infiltration and fibrosis, leading to a diagnosis of IgG4-AIP. The patient responded well to corticosteroid therapy, with clinical and radiologic improvement, and was placed on low-dose maintenance therapy to prevent recurrence. IgG4-AIP should be considered in patients with idiopathic recurrent pancreatitis, and early recognition is crucial to avoid unnecessary interventions. Corticosteroids remain the mainstay of treatment, but long-term monitoring is essential due to the risk of recurrence and potential complications.