Autoimmune pancreatitis (IgG4-related)

Autoimmune pancreatitis, type 1, affects the pancreas and is understood as the pancreatic expression of a broader condition called IgG4-related disease, which can also involve the bile ducts, salivary glands, kidneys, and lymph nodes. The immune system is thought to drive chronic inflammation of the pancreas, marked by elevated IgG4 antibody levels, dense lymphoplasmacytic infiltration, and a distinctive pattern of scarring called storiform fibrosis, and this swelling can be mistaken for a pancreatic tumor on imaging. Type 1 disease most often appears in the seventh decade of life and shows a strong male predominance.

It is considered rare, and most of the available epidemiological data comes from Japan, where a nationwide survey identified thousands of affected patients, while research from Europe and other regions remains more limited, so a precise global prevalence figure is not well established.

Common signs

painless jaundice (yellowing of skin and eyes from blocked bile ducts) is the most common sign; others include weight loss, mild abdominal discomfort, and new or worsening blood sugar problems.

This is a plain-language summary for orientation, not a diagnosis. Mechanisms are described as current understanding, not settled fact. Work with your own clinician for your care.