Close relationship between autoimmune pancreatitis and multifocal fibrosclerosis

Abstract

Background: Autoimmune pancreatitis is a unique clinical entity proposed recently, and is sometimes associated with inflammation of other organs.

Aims: To examine the pathophysiology of the pancreas and other organs in patients with autoimmune pancreatitis.

Patients and methods: We evaluated clinicopathological findings in six resected and one autopsied patient with autoimmune pancreatitis. The pancreas, peripancreatic tissue, bile duct, and gall bladder were examined histologically and immunohistochemically. Biopsied salivary gland and cervical lymph node of one patient were also examined. We also performed similar immunohistochemical examinations in pancreatectomy specimens from 10 patients with alcoholic chronic pancreatitis and biopsied salivary glands from five patients with Sjögren's syndrome.

Results: Stenosis of the extrahepatic bile duct was detected in all patients. Histological findings were characterised by diffuse lymphoplasmacytic infiltration with marked interstitial fibrosis and acinar atrophy, obliterated phlebitis of the pancreatic veins, and involvement of the portal vein. Immunohistochemically, diffusely infiltrating cells consisted predominantly of CD4 or CD8 positive T lymphocytes and IgG4 positive plasma cells. Similar inflammatory processes also involved the peripancreatic tissue, extrahepatic bile duct, gall bladder, and salivary gland. Lymph nodes were swollen with infiltration of IgG4 positive plasma cells. None of these findings was seen in alcoholic chronic pancreatitis or Sjögren's syndrome.

Conclusions: The development of the specific inflammations in extensive organs as well as the pancreas in patients with autoimmune pancreatitis strongly suggests a close relationship between autoimmune pancreatitis and multifocal fibrosclerosis.

Figure 1

Characteristic low power view of the pancreas showing prominent interstitial fibrosis with marked atrophy of the exocrine pancreas and diffuse inflammatory cell infiltration throughout the pancreas (haematoxylin-eosin, ×8)

Figure 2

Periductal non-occlusive fibrosis with lymphoplasmacytic infiltration and irregular condensation, and rupture of the elastic fibres of the pancreatic ductal wall. ((A) Haematoxylin-eosin, ×24; (B) Elastica Van Gienson, ×24.)

Figure 3

Pancreatic vein showing complete luminal obliteration with prominent cellular infiltrates and fibrosis ((A) Elastica Van Gienson, ×50). Infiltration of IgG4 positive plasma cells was detected in the obliterated vein and in the interstitium around it ((B) immunostaining of IgG4, ×50).

Figure 4

Many IgG4 positive plasma cells infiltrated around the pancreatic duct ((A) immunostaining of IgG4, ×40) and the common bile duct ((B) immunostaining of IgG4, ×40). Infiltration of IgG4 positive plasma cells was detected in the salivary gland ((C) immunostaining of IgG4, ×100) and cervical lymph node ((D) immunostaining of IgG4, ×80).