Endocrine Abstracts

Background: Autoimmune pancreatitis (AIP) is a relatively new entity in which the exocrine pancreas shows lymphocytic infiltration. There are two subtypes of AIP; Type 1 related with Immunoglobulin G4 (IgG4) as the pancreatic manifestation of IgG4-related disease (IgG4-RD), and Type 2 related with granulocytic infiltration. The characteristic features of Type 1 AIP are increased serum IgG4 levels, lymphoplasmacytic sclerosing pancreatitis (infiltration of IgG4+ plasmacytes and lymphocytes, storiform fibrosis, and obliterative phlebitis), extra-pancreatic manifestations of IgG4-RD (e.g. sclerosing cholangitis, sclerosing sialadenitis, retroperitoneal fibrosis), and steroid responsiveness.

Case: A 60 years-old male was sent to our Endocrinology outpatient clinic because of elevated fasting blood sugar levels found during his Chest Diaseases Department follow-ups due to bronchiectasis and multiple lung cysts. His initial fasting blood glucose was 123 mg/dl. A 75-gr oral glucose tolerance test was performed and second hour glucose level was found as 246 mg/dl. Subsequent HbA1c measurement was 8.62%. In his background he had undergone lung surgery for cyst excision and tuberculosis treatment for a year. He had no first degree relative with diabetes in his family history. He had weakness, remarkable weight loss and serious postprandial dyspeptic symptoms. In his physical examination his BMİ was 22.4 kg/m² and no conspicuous finding except of abdominal tenderness was found. A diffusion magnetic resonance imaging of pancreas was performed according to negative family history for diabetes, weight loss and sudden presentation of diabetes in advanced age to rule out a possible pancreatic neoplasm. Pancreas MRI revealed a diffuse thickened and edematous pancreas with loss of lobulated appearance and an evident pancreatic duct. These findings were interpreted in favor of autoimmune pancreatitis. Afterwards the patient was examined for autoimmune diabetes. Anti glutamic acid decarboxylase, islet cell and insulin autoantibodies were all negative. Serum IgG4 levels were elevated (150 mg/dl), suggesting a possible IgG4-RD since the actual criteria for IgG4-RD implies a cut-off value of serum IgG4>135 mg/dl. We presumably thought that cystic lung disease and autoimmune pancreatitis could be manifestations of IgG4-RD and consequently IgG4 related pancreatitis can be the cause of deterioration of both exocrine and endocrine funtions of pancreas for this patient. On this basis we thought that diabetic condition of the patient could be secondary to IgG4 related AIP.

Conclusion: The concomitant onset of autoimmune pancreatitis and autoantibody positive type 1 diabetes has been described among IgG4-RD. But our case is suggesting a unique immune disturbance that compromises the pancreatic endocrine and exocrine functions.