Autoimmune Pancreatitis

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Autoimmune Pancreatitis

• Presented by
• Tamer Mahmoud El-Baz

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Introduction

• Autoimmune pancreatitis (AIP) is a form of
  chronic pancreatitis that has unique clinical,
  morphologic, and histologic features.

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Pathogenesis

• Immunologic mechanisms appear to be the cause,
  given the characteristic histologic findings of
  lymphoplasmacytic infiltration (the hallmark of
  the disease) , prevalence of hypergammaglobulinemi
  a, autoantibodies, and response to steroids.

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• Elevated levels of gammaglobulins is a
  characteristic finding.
• There are 9 Ig isotypes IgM, IgD, IgE, IgG (four
  subclasses IgG1, IgG2, IgG3 and IgG4) and IgA
  (subclasses IgA1 and IgA2). IgG4 accounts for 3
  to 6 of total IgG in normal subjects.
• Elevated levels of the IgG4 subclass is a
  sensitive and specific marker for AIP but not for
  cancer pancreas, chronic pancreatitis, PSC or
  PBC. These levels decrease but do not normalize
  in the majority of patients with AIP after
  steroid therapy.

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• Other antibodies, including antinuclear,
  anti-smooth muscle, antihuman lactoferrin, and
  anticarbonic anhydrase II antibodies have been
  described in patients with AIP. However, none of
  them proved to be specific or sensitive.
• Like other autoimmune diseases, AIP is associated
  with a particular HLA haplotype.

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Clinical Features

• AIP is diagnosed more commonly in
• Male patients, with a 21 predominance over
  female patients.
• Age of presentation is variable, ranging from 30
  to 80 years, but it is more common in the sixth
  decade. If associated with other autoimmune
  disorders, it may present at a younger age.

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• It is commonly mimicking pancreatic carcinoma.
• Jaundice is frequent mostly from infiltration of
  CBD.
• Abdominal pain, if present, is mild. Back pain
  may also be present.
• Weight loss may be significant.
• Anorexia is not a common feature.
• It may present with idiopathic pancreatic
  steatorrhea as well as insulin-dependent diabetes
  or glucose intolerance.

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Extrapancreatic

• Other associations include
• Stenosis of the bile duct.
• Enlargement of the salivary glands.
• Abdominal or cervical lymphadenopathy.
• Retroperitoneal fibrosis.
• Stenosis of the peripancreatic arteries or portal
  vein.

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Diagnosis Radiographic Features

• Abd U/S an enlarged, hypoechoic gland is seen.

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• Abd CT
• a 'sausage-shaped,' diffusely enlarged pancreas,
• delayed and prolonged contrast enhancement,
• absence of main pancreatic duct dilation,
• Pancreatic calcification is uncommon and may
  develop after multiple relapses.

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Conventional US (a.) diffuse enlargement of the
body-tail of the pancreas can be observed. CT
(b. c. d.) the pancreas shows diffuse delayed
enhancement (b. c.) with a peripheral rim of
enhancement during the distribution phase (d.),
about 5 minutes after the contrast injection.
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• MRI A hypointense gland with delayed enhancement
  on T2W.

stenosis of the main pancreatic duct as well as
of the intrapancreatic portion of the biliary duct
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• ERCP usually shows a focal to diffuse,
  irregular, and attenuated pancreatic duct. In
  patients with focal-strictures, absence of
  upstream dilation of the pancreatic duct is
  characteristic.

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• EUS features of autoimmune pancreatitis are
  easily mistaken for malignancy. However, a
  diffusely hypoechoic, enlarged pancreas, together
  with chronic inflammatory cells in aspirated
  cytologic specimens, is supportive of the
  diagnosis of AIP.

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Diagnosis Biopsy

• It is difficult to make the diagnosis on the
  basis of fine-needle aspiration of the pancreas.
  The diagnosis cannot be definitively made unless
  characteristic obliterative phlebitis or
  lymphoplasmacytic infiltration is seen
  surrounding a duct.

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inflammatory infiltrates concentrated around the
duct
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Treatment

• Diet and lifestyle
• Small and frequent meals, and a low-fat diet to
  minimize postprandial pancreatic secretion and
  resultants pain.

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• Pharmacologic treatment
• Steroid therapy is usually effective although the
  evidence is still empiric.
• It is recommended in patients with moderate
  abdominal and back pain, obstructive jaundice due
  to stenosis of the common bile duct by the
  inflamed pancreas, or sclerosing cholangitis.
• It occasionally ameliorates DM associated with
  AIP, irrespective of clinical phenotype.

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• In patients with OJ and infection, biliary
  drainage and administration of antibiotics should
  be performed prior to steroid therapy.
• Antacids or anticholinergic agents may be used to
  minimize stimulation of pancreatic exocrine
  function.

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• Clinical signs and symptoms of improvement
  include
• Decreased jaundice, abdominal and back pain.
• Decreased pancreatic swelling on imaging and
  decreased stenosis of the pancreatic and CBD.
• Decreased serum levels of pancreatic enzymes,
  hepatobiliary enzymes and total bilirubin.
• Recovery of pancreatic exocrine and endocrine
  function (blood sugar, hemoglobin A1c, and
  insulin response).

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• Endoscopic therapy
• The aim is stenting of the CBD when obstructed ,
  this may be either by
• Endoscopic nasobiliary drainage.
• ERCP.

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• Surgery
• Indication pancreatic or bile duct cancer that
  is hard to rule out on ERCP images or poor
  efficacy of steroid therapy.
• The procedure performed removal of segmental
  stenosis of the pancreatic or CBD.
• Complications Being on steroid therapy, the risk
  of leakage of bile and pancreatic juice is high.
  Benign strictures of the CBD may occur at the
  anastomosis site.

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