What Is Autoimmune Pancreatitis?

Autoimmune pancreatitis (AIP) is benign, fibrous inflammatory chronic pancreatitis. It has unique clinical manifestations, imaging and pathological characteristics, and has been found to be associated with hypergammaglobulinemia, and the effect of corticosteroid treatment is good. In 1995 Yoshida et al. Proposed the concept of autoimmune pancreatitis.

Basic Information

Visiting department

Gastroenterology

Multiple groups

Men over 50

Common causes

Autoimmune

Common symptoms

Obstructive painless jaundice

Clinical manifestations of autoimmune pancreatitis

Chronic inflammatory lesions of the pancreas caused by autoimmunity. It accounts for 2% to 6% of cases of chronic pancreatitis. It is more common in elderly men, mostly 50 years of age. The main clinical manifestation is obstructive painless jaundice, accounting for 70% to 80% of patients. Most of them are focal lesions of the pancreatic head, which can also be manifested as acute diffuse pancreatitis. AIP can cause a decrease in pancreatic (diabetes, weight loss) and exocrine (lipid diarrhea, weight loss) functions. Focal patients are difficult to distinguish from malignant tumors, and about 23% of AIPs are surgically treated because they are mistaken for malignant tumors.

Autoimmune pancreatitis test

1. Serum IgG ₄ levels

The serum IgG ₄ level of patients with AIP was significantly higher than that of normal people.

2. Increased eosinophils

Activated CD4, CD8 positive, hypergammaglobulinemia, presence of autoimmune antibodies (antinuclear antibodies, antimitochondrial antibodies, anti-CA-II antibodies, rheumatoid factors, anti--fodrin antibodies, anti-smooth muscle antibodies).

3. Ultrasound (US)

AIP is characterized by low echo-dominated diffuse pancreatic enlargement on US examination.

4. Radiographic examination (CT / MRI)

(1) Pancreatic manifestations AIP changes in the pancreas itself can be diffuse and focal, but the exudation around the pancreas is less severe than pancreatic fluid exudative pancreatitis, which is generally limited to the periphery of the pancreas. In addition, calcification, cystic degeneration, and pseudocyst formation are rare. The CT density of the lesion was reduced, and the enhancement was reduced. Magnetic resonance manifestations were low T ₁ WI and slightly higher T ₂ WI; capsule-like changes around the pancreas showed low T ₂ WI.

(2) Endoscopic ultrasonography (EUS) has fewer blind spots in the pancreatic head and tail, and the application of high-frequency ultrasound (7.5 to 20 MHz) can obtain the fine structure of the lesion, which is manifested by diffuse pancreatic enlargement and localized swelling based on low echo Big.

(3) Endoscopic retrograde cholangiopancreatography (ERCP ) The pancreatic duct stenosis image displayed by ERCP is characteristic of autoimmune pancreatitis. Infiltration and fibrosis of inflammatory cells around the pancreatic duct are the cause of stenosis. The main pancreatic duct is usually thin, the wall is not smooth, and the upper pancreatic duct is not significantly dilated. The length of the narrow image is more than 2/3 of the main pancreatic duct is diffuse, and the range of more than 1/3 and less than 2/3 is limited.

(4) Fluorine-18-fluorodeoxyglucose-positron emission tomography (18F-FDG PET / CT) When the inflammation of the AIP is obvious, the FDG in the lesion is highly accumulated, and the SUV examination values are all above 3.5. When AIP has lesions in the pancreas, FDG accumulates in the pancreas.

Diagnosis of autoimmune pancreatitis

The main diagnosis is based on: special imaging findings; serological examination; histological examination; effective hormone therapy; lesions outside the pancreas. Focal AIP is clinically and radiographically similar to pancreatic cancer.

Autoimmune pancreatitis treatment

Drug treatment

The standard treatment for AIP is hormone therapy; if hormone therapy is not effective, the possibility of other lesions, such as pancreatic cancer, should be considered. Recurrence can occur in 6% to 54% of patients. Focal AIP has more recurrence than diffuse AIP, and hormonal therapy can be repeated when recurrence occurs. Immunosuppressive drugs that have no effect on hormone therapy can also be used. In the acute phase, fasting, high-calorie intravenous infusion, and anti-pancreatin preparations should be given. During the remission period, the drug can be used alternately intravenously and orally. The pancreas has low exocrine function during progressive pancreatic atrophy and can be treated with digestive enzymes. Chronic pancreatitis is generally not treated with steroid hormones.

2. Endoscopic treatment

In the acute phase, due to the inflammation of the pancreatic duct, the bile ducts become thinner and bile flows poorly. Endoscopic and external fistulas are performed under endoscopy to improve the enlarged pancreas.

3. Surgical treatment

Pancreatic stones and intractable pain and pseudocysts should be surgically treated. In addition, surgical exploration should be performed when tumorigenic pancreatitis and pancreatic cancer cannot be distinguished.