Autoimmune pancreatitis

Introduction to autoimmune pancreatitis Autoimmune pancreatitis (AIP) is an inflammatory disease of the pancreas that results from an immune response in which the pancreas produces an antigen as an antigen from a CD4-positive helper cell. Compared with common causes of chronic pancreatitis, AIP has a relatively typical performance: elderly patients with obstructive jaundice without acute pancreatitis, high gamma globulinemia and elevated serum IgG4 levels, autoantibodies positive, irregular Pancreatic duct stenosis and diffuse enlargement of the pancreas, pathology suggests fibrosis with significant infiltration of chronic inflammatory cells such as T lymphocytes and plasma cells. basic knowledge Sickness ratio: 0.5% Susceptible people: no specific population Mode of infection: non-infectious Complications: Diabetes

Causes of autoimmune pancreatitis

All autoimmune pathological mechanisms may be the cause of autoimmune pancreatitis, such as sjögren syndrome, autoimmune diseases such as sclerosing cholangitis and pancreatitis.

Sjögren syndrome (38%):

Sjgren syndrome is a chronic inflammatory disease characterized by severe mucosal dryness in the eyes, mouth and other areas. The disease often presents with specific symptoms of rheumatoid arthritis or systemic lupus erythematosus. The cause is unclear and some people think it is an autoimmune disease. The incidence is lower than rheumatoid arthritis, more women than men.

Sclerosing cholangitis (40%):

Sclerosing cholangitis refers to a series of syndromes characterized by cholangitis and obstructive jaundice due to incarceration of the gallbladder neck or cystic duct stones and/or other benign diseases that cause compression or inflammation to cause obstruction of the common hepatic duct or common bile duct. .

Pathogenesis

Classification

(1) pancreatic duct stricture chronic pancreatitis: all pancreatic ducts through which the main pancreatic duct passes are thin, irregular and accompanied by obvious enlargement of the pancreas, diffuse inflammation of the pancreas, hypergammaglobulinemia and autoantibodies, pancreas Lymphocyte infiltration with high fibrosis, steroid therapy has a significant effect, also known as duct-narrowing autoimmune related pancreatitis (DNAIP).

(2) Localized pancreatic duct stricture chronic pancreatitis: changes in irregular inflammation of the non-stenotic or branching part of the pancreatic duct corresponding to diffuse stenotic pancreatitis, pancreatic duct stricture chronic pancreatitis and limitations Chronic pancreatic duct stricture chronic pancreatitis is interrelated. The localized type may be a diffuse initial stage or a period of healing. The diffuse type is a limited type of diseased period. Therefore, the length of the pancreatic duct stenosis is 2/3. The above is considered to be a diffuse stenosis type, which is considered to be a limited type below 2/3, which is the basis for the diagnosis of diffuse stenotic pancreatitis, except for the limited lesions and tumorous changes shown by short stenosis.

2. Pathology

(1) Pancreas: The pancreas is enlarged, hardened, and there is no clear tumor formation. Fibrosis can be seen on the section. The gland maintains the original lobular structure. The pancreatic capsule is fibrous hypertrophy, especially the thicker fibrosis on the portal vein side.

Histologically, obvious lymphocytic infiltration and fibrosis and pancreatic lobular interstitial enlargement, lymphoid follicle formation, fibrosis can affect the pancreatic lobule, there may be atrophy of the gland, fibrosis around the pancreatic duct is more obvious than glandular inflammation The original elastic fibers around the pancreatic duct are loose, proliferating, near-lumen lymphocytes and inflammatory cell infiltration or collagen fibrosis, pancreatic duct lumens become smaller, lymph nodes are enlarged, lymphoid follicles are proliferated, and epithelial cells are small. Cluster nests.

The infiltration of T cells around the duct is more pronounced than that of B cells. The T cell subset is predominantly CD4 positive and may also be CD8 positive.

Obvious eosinophil infiltration of cholangitis and fibrosis around the pancreas, fibrosis and inflammatory cell infiltration involving adipose tissue and connective tissue around the pancreatic parenchyma, the ventral side of the pancreas exceeds the elastic fibers, and the dorsal side involves the portal vein, reaching the pancreatic papilla To a wide range of pancreatic ends.

The veins inside and outside the pancreas are occluded by inflammatory cell infiltration, which is altered by occlusive phlebitis. There is no specific change in the arteries. There is fibrosis around the small arteries. The inner cavity of the intima is narrowed.

(2) bile duct, gallbladder lesions: pancreatic bile duct wall hypertrophy, stenotic bile duct mucosal surface smooth, diffuse hyperplasia of the original bile duct mucosa, upper and middle bile duct hypertrophy, pancreatic bile duct changes than pancreatic bile duct Obviously, all lymphatic infiltration and fibrosis of the bile duct wall, edema with hypertrophy, involving the bile duct, duct and glandular and duodenal wall, gallbladder wall hypertrophy, but no change in histological bile duct wall.

Autoimmune pancreatitis prevention

Autoimmune pancreatitis has a recurrent trend. Preventive measures include removing the cause and avoiding incentives such as abstinence, overeating, and hyperlipidemia. Cholelithiasis plays an important role in the pathogenesis of autoimmune pancreatitis. Therefore, patients with cholelithiasis with a history of autoimmune pancreatitis should undergo elective cholecystectomy and common bile duct exploration. For patients with existing autoimmune diseases such as Grves disease and SLE with pain in the left upper abdomen, the possibility of this disease should be suspected. Early detection and early treatment are the key to prevention.

Autoimmune pancreatitis complications Complications diabetes

80% impaired glucose tolerance in autoimmune pancreatitis, diabetes symptoms before treatment, glucose tolerance in steroid therapy, glucose tolerance, 80% exocrine function, half normalization by steroid therapy The mechanism of impaired glucose tolerance is considered to be a sudden inflammatory cell infiltration and fibrosis associated with pancreatic exocrine blood flow disorder, causing islet blood flow disorders.

Autoimmune pancreatitis symptoms common symptoms pancreatic fibrosis back pain abdominal pain

No specific symptoms, abdominal symptoms can be mild abdominal pain and back pain, obstructive jaundice is also common, with the Sjögren syndrome as the representative of autoimmune disorders combined, others such as membranous nephritis, impaired glucose tolerance, Sclerosing cholangitis, chronic rheumatoid arthritis, chronic thyroiditis can also be combined with autoimmune pancreatitis, of which the highest rate of diabetes mellitus, diabetes associated with diabetes can occur type I diabetes, but relatively more type II diabetes Improvements in steroid therapy, on the one hand, improvement in pancreatitis, may also have a tendency to worsen diabetes, not only in the pancreas, but also in cases where sclerosing cholangitis and similar lesions are present, steroid hormones are also effective.

Examination of autoimmune pancreatitis

Eosinophil

Increased, activated CD4, CD8 positive, hypergammaglobulinemia, increased IgG and IgG4, autoimmune antibodies (antinuclear antibodies, anti-mitochondrial antibodies, anti-CA-II antibodies, rheumatoid factor, anti--fodrin antibodies, anti- Smooth muscle antibody).

2. Blood and urine trypsin

Elevation-normal-lower is possible, 40% to 50% increase, and 60%-70% increase in hepatobiliary enzymes and bilirubin.

3. Pancreatic function test

The pancreatic chymase test had a low factor of 3, a BT-PABA excretion test of 81%, a diabetic type of 68%, a critical type of 13%, and an endocrine abnormality of 84%.

4.US

Autoimmune pancreatitis is characterized by low echo-based diffuse pancreatic enlargement on ultrasound, with diffuse enlargement accounting for 69% and localized enlargement accounting for 31% (24% of pancreatic head, pancreatic tail) 7%), no cases of pancreatic atrophy, 9% pancreatic islets, 7% of pancreatic cysts. When the pancreas is constricted, it should be differentiated from pancreatic cancer. The internal echo of pancreatic cancer is uneven, and there is a high echo in the center. The pancreatic duct is highly smooth and bead-like, and the autoimmune pancreatitis has no pancreatic duct dilatation or slightness, and the shape is smooth and common.

5.CT

The diffuse enlargement of the pancreas is characterized by the fact that the dynamic contrast imaging of the early stage of the lesion is not sufficient, and the phase contrast of the late phase contrast is characterized by delayed enhancement.

6.EUS

Compared with the in vitro US, there is less blind zone in the pancreatic head and pancreas. High-frequency ultrasound (7.5-20MHz) can be used to obtain the fine structure of the lesion, which is also characterized by diffuse pancreatic enlargement and localized enlargement.

7.ERCP

The image of pancreatic duct stenosis revealed by ERCP is a feature of autoimmune pancreatitis. Inflammatory cell infiltration and fibrosis around the pancreatic duct are the cause of stenosis. The main pancreatic duct is usually thin, the wall is not complete, and the upper pancreatic duct is not significant. In the expansion, the length of the narrow image is more than 2/3 of the main pancreatic duct, and the range of 1/3 or more and 2/3 or less is limited.

8.FDG-PET inspection

In autoimmune pancreatitis, when the inflammation is the heaviest, the FDG in the lesion is highly accumulated, and the SUV examination value is all above 3.5. After the inflammation subsides or the steroid hormone therapy is effective, the FDG aggregation is reduced, the FDG accumulation disappears during the remission, and the autoimmune When pancreatitis is present in the whole pancreas, FDG is characteristic of total pancreatic accumulation. However, FDG also accumulates in the whole pancreas when pancreatic head cancer and pancreatic tail tumor are associated with pancreatitis. This alone is different from other diseases. Difficult, can not be diagnosed with autoimmune pancreatitis and malignant tumors.

Diagnosis and diagnosis of autoimmune pancreatitis

diagnosis

Diagnostic conditions for pancreatic duct stricture autoimmune pancreatitis:

1. Pancreatic duct stenosis with pancreatic enlargement.

2. Blood tests for hypergammaglobulinemia or have autoantibodies.

3. Pancreatic histology has a high degree of lymphocytic infiltration and fibrosis.

4. Treatment of clinical symptoms with steroids.

Meet 1 and 2 diagnoses; meet 1 and 3 accurate diagnoses; meet 1 and 4 suspicious diagnoses.

Differential diagnosis

Pancreatic cancer

Typical pancreatic cancer CT can be diagnosed.

2. Tumor-forming chronic pancreatitis

Cases with tumorous lesions of the suspected pancreatic head of the jaundice and imaging findings of the head of the pancreas require surgery to determine the nature.

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