Autoimmune pancreatitis starting as a localized form.

Area of Science:

• Gastroenterology
• Immunology
• Radiology

Background:

• Autoimmune pancreatitis (AIP) is a rare pancreatic condition driven by autoimmune processes.
• It typically presents with diffuse pancreatic swelling and ductal stenosis, often termed "sclerosing" pancreatitis.
• Complete disease progression is documented, but initial localized forms with follow-up imaging are rarely reported.

Observation:

• A 56-year-old man presented with obstructive jaundice and a hypoechoic pancreatic head mass on ultrasonography.
• Endoscopic retrograde pancreatography revealed localized pancreatic duct stenosis, and CT showed an enlarged pancreatic head with a capsule-like rim.
• After four months, imaging demonstrated diffuse pancreatic swelling and ductal narrowing, accompanied by new-onset glucose intolerance.

Findings:

• The patient received steroid therapy, leading to normalization of pancreatic duct imaging and resolution of pancreatic swelling on CT within two months.
• Obstructive jaundice and glucose intolerance were alleviated, and the biliary tube was removed.
• This case highlights autoimmune pancreatitis initially presenting as a localized, mass-forming type with characteristic imaging features.

Implications:

• Awareness of the localized form of autoimmune pancreatitis is essential for accurate diagnosis.
• Prompt steroid treatment can effectively manage this condition, reversing imaging abnormalities and clinical symptoms.
• This case underscores the importance of comprehensive imaging and clinical follow-up in diagnosing rare pancreatic diseases.