Diagnostic Criteria for Autoimmune Pancreatitis

Autoimmune pancreatitis (AIP) can be challenging to diagnose due to its similarity with pancreatic cancer. However, several established criteria help clinicians accurately identify the condition. The Asian diagnostic standards are widely referenced and include three major components: imaging features, serological markers, and histopathological findings.

Radiological Features

The first requirement involves characteristic imaging findings. AIP often presents as focal or diffuse enlargement of the pancreas with a nodular or low-density margin. Additionally, imaging may reveal localized or widespread narrowing of the pancreatic and bile ducts, commonly accompanied by biliary strictures. These radiological changes are essential for diagnosing AIP and must both be present.

Serological Markers

Serological testing plays a supportive role in diagnosis. Elevated serum IgG4 levels are a hallmark of AIP, although high total IgG levels can also be observed. In some cases, other autoantibodies may test positive, even if IgG4 is not elevated. Only one abnormal serological result is required to fulfill this criterion.

Histopathological Confirmation

Histological evaluation provides the most definitive evidence. Characteristic features include lymphoplasmacytic infiltration combined with fibrosis and a high concentration of IgG4-positive plasma cells. When available, histopathological examination of pancreatic tissue significantly enhances diagnostic accuracy. Similarly, specimen-based pathological analysis offers strong support for confirming AIP.

In summary, the diagnosis of autoimmune pancreatitis relies on a combination of imaging abnormalities, serological indicators, and histological confirmation. Meeting these criteria helps ensure accurate identification and appropriate management of the disease.