Histopathological features of diagnostic and clinical relevance in autoimmune pancreatitis: a study on 53 resection specimens and 9 biopsy specimens

Abstract

Background and Aims: Autoimmune pancreatitis seems to be a disease with a heterogeneous appearance. Our intention was to establish key diagnostic criteria, define grades of severity and activity, identify features of potential subtypes and evaluate the diagnostic relevance of biopsy specimens. Methods: Histopathological criteria and clinical features were recorded in pancreatic resection specimens from 53 patients who were found to have chronic pancreatitis lacking pseudocysts, calculi, irregular duct dilatations, pancreas divisum and/or duodenal wall inflammation. The severity of the chronic inflammation was graded, and the activity of the acute inflammatory component and the granulocytic epithelial lesion (GEL) were determined. Additionally, pancreatic biopsy specimens from 9 patients with suspected AIP were assessed. Results: Periductal lymphoplasmacytic infiltration was identified in all cases, followed in order of frequency by periductal fibrosis and venulitis. These changes were absent in 147 pancreatic specimens that showed chronic pancreatitis associated with pseudocysts, calculi, pancreas divisum and/or duodenal wall inflammation. In 90% of the cases, these chronic changes were graded as 3 or 4. In 81%, the inflammatory process resided in the head of the pancreas and involved the common bile duct. GELs were present in 42% of the patients, who had a mean age of 40.5 years, an almost equal male-female ratio and a high coincidence of ulcerative colitis or Crohn's disease. Patients without GELs were older (mean age 64 years), showed a male preponderance, commonly had Sjögren's syndrome and often developed recurrent bile-duct stenosis. Diagnostically relevant lesions were present in two of five wedge biopsy specimens and three of four fine-needle specimens. Conclusions: Periductal lymphoplasmacytic infiltration and fibrosis, preferential occurrence in the pancreatic head and venulitis characterize autoimmune pancreatitis. GELs predominantly occur in a subset of patients who are younger, more commonly have ulcerative colitis and Crohn's disease and seem to have fewer recurrences than patients without GELs. Pancreatic biopsy material proved to be a very helpful adjunct for establishing the diagnosis.

IgG4-associated cholangitis: a comparative histological and immunophenotypic study with primary sclerosing cholangitis on liver biopsy material

“…Furthermore, autoimmune pancreatitis is a uncommon disease, the largest surgical series, a multicentric study, included only 62 autoimmune pancreatitis cases. 20 Additional studies are required to understand the natural history of this hepatobiliary disease in individuals with concurrent pancreatic disease, and in those who lack pancreatic involvement, but whose liver biopsy samples show histological or immunological features of IgG4-associated cholangitis.…”

An Experimental Model of Autoimmune Pancreatitis in the Rat

“…At presentation, only 8 to 25% of such patients have other recognized autoimmune diseases such as Sjogren sialadenitis, inflammatory bowel disease, or sclerosing cholangitis. 13 Because of pancreatic enlargement that may be confined to the head, many patients have undergone pancreatic resection because pancreatic carcinoma was suspected. 5 Histopathological examination of resection specimens has allowed the recognition of characteristic duct-centric inflammation characterized by the presence of lymphocytes and plasma cells within the duct wall and periductal connective tissue.…”

“…These lesions (granulocytic epithelial lesions) have been likened to the crypt abscesses seen in ulcerative colitis, and are most likely to be seen in patients that also have inflammatory bowel disease. 13 The disease may be localized or less commonly diffuse within the pancreas. Part of the variability in humans is attributed to the duration and severity of the process, but it is possible that part of the variability between cases reflects involvement of distinct epitopes.…”

Autoimmune pancreatitis in Japan: overview and perspective

“…Recommendation for Steroid Therapy of Autoimmune Pancreatitis [23][24][25]. It is reported that AIP with GEL has different clinical characteristics from AIP with LPSP, such as occurrence at younger age, lack of serum IgG4 elevation and frequent complication of inflammatory bowel diseases.…”

“…Recently, an increasing number of case reports have been made from outside of Japan, confirming that this disease exists beyond regions and races. With accumulation of international information on AIP, it is becoming clear that there are different types resembling AIP [23][24][25]. In addition, several other diagnostic criteria of AIP were proposed from several countries such as Korea [26], the US [27] and Italy [18].…”