Autoimmune Pancreatitis Presenting as Obstructive Jaundice Mimicking Pancreatic Cancer: An Unusual Case Report

Autoimmune pancreatitis (AIP) is a rare form of chronic pancreatitis that can be misdiagnosed as pancreatic cancer due to similar clinical and radiological findings. In this case report, we present a 49-year-old male patient who presented with obstructive jaundice and was initially diagnosed with pancreatic cancer based on imaging findings. However, the lack of definitive parenchymal tissue in the biopsy raised suspicion for an alternative diagnosis, which led to further testing and ultimately the diagnosis of AIP. The use of endoscopic ultrasonography (EUS) and fine needle biopsy (FNB) helped to obtain a tissue diagnosis and rule out malignancy. The measurement of serum IgG4 levels further supported the diagnosis of AIP. The patient was treated with glucocorticoids and showed gradual improvement, ultimately recovering from AIP. This case highlights the importance of maintaining a high level of suspicion and considering AIP as a possible diagnosis when investigating cases that mimic pancreatic cancer. Early recognition and treatment with steroids can result in a favorable outcome for patients with AIP.