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In a leading article published in Gut in 1990, Sarles et al made the opening comment that “there have been few efforts to classify diseases of the pancreas by their specific pathological features and causes... “.1 Indeed, the classification of pancreatitis is fraught with a major difficulty, that of developing a comprehensive system which embodies aetiology, pathogenesis, clinical features, and pathological findings. The 1984 Marseille-Rome classification included three types: acute pancreatitis, chronic pancreatitis and obstructive pancreatitis.2 The 1992 Atlanta classification dealt almost exclusively with acute pancreatitis.3
In the West, chronic alcoholism and biliary tract disease are probably the two most common causes of chronic pancreatitis and account for approximately 80% of cases. Other rarer causes include heredity, hyperparathyroidism, haemochromatosis, hyperlipoproteinaemia and pancreatic carcinoma. In addition to the above, malnutrition and environmental factors may account for chronic pancreatitis in tropical areas of Asia and Africa.
Ten to forty per cent of patients (the numbers differ in published series) have so called idiopathic chronic pancreatitis—that is, chronic pancreatitis in which no identifiable aetiological factor can be incriminated with certainty. Patients with idiopathic chronic pancreatitis tend be older than those with alcoholic related chronic pancreatitis. Inclusion of patients in the idiopathic chronic pancreatitis group obviously requires strict clinical criteria, and particularly evidence that patients have abstained from alcohol consumption and also have none of the other recognised causes of chronic pancreatitis. However, the identification of the alcoholic patient may be notoriously difficult. In a series of 66 patients with idiopathic chronic pancreatitis, Layer at al excluded all patients who consumed a moderate or unknown amount of alcohol.4
From the pathologist’s viewpoint, the three histological hallmarks of chronic pancreatitis are fibrosis, inflammation and glandular atrophy.5 ,6 These lesions are unevenly distributed within the exocrine parenchyma and their number varies depending on the stage of disease. Fibrosis may be periductal, intralobular or interlobular (perilobular) in distribution. The inflammatory infiltrate is of the chronic type and comprises lymphocytes, plasma cells and macrophages, but rarely polymorphs. The glandular lobules or acini are disrupted, but the lobular pattern tends to be preserved even in advanced disease. Other morphological features include ductal alterations, particularly duct distortion and dilatation, cyst formation, protein plugging, and calcified calculi. The epithelium lining the involved ducts shows variable changes such as hyperplasia, metaplasia or atrophy. The result of these morphological changes is an irreversible scarring of the exocrine pancreas, but, curiously, the endocrine islets are relatively resistant. It should be remembered that the presence of intraductal calcified calculi in chronic pancreatitis has been responsible for the generic term chronic calcifying pancreatitis which is still frequently used by pathologists.
Until recently, it was thought that all forms of chronic pancreatitis, irrespective of their aetiology, were characterised by identical or almost identical pathological changes. For instance, tropical chronic pancreatitis related to protein deficiency is grossly and microscopically indistinguishable from “Western” chronic pancreatitis resulting from alcohol misuse.
Ectors et al, in this issue (see page 263), present a multicentre clinicopathological study of 12 patients who were surgically treated for apparent non-alcoholic chronic pancreatitis. There were two women and 10 men with a mean age of 44 (range 17–77) years. Four of these patients also had an associated autoimmune related disease, respectively, Sjögren’s syndrome, primary sclerosing cholangitis, chronic ulcerative colitis, and anorectal Crohn’s disease. None of the patients had a history of cholelithiasis. All but one patient did well after surgery, irrespective of the type of surgical procedure used (total pancreatectomy, duodenohemipancreatectomy or distal pancreatectomy). In effect, these 12 patients seemed to belong to the idiopathic chronic pancreatitis group.
The main interest of the above study lies in the recognition and description of several histopathological changes (supported by immunohistochemical findings) which were different from those commonly seen in alcoholic chronic pancreatitis, when compared with a control group. In particular, these changes included a predominant T cell lymphocytic infiltrate around interlobular ducts (especially medium sized ones), with resulting duct obstruction and occasionally duct destruction, as well as acinar fibrosis. Calcification, pseudocysts and fat necrosis were not found. There was also no significant difference in the pancreatic lesions between the four patients with and the eight without associated autoimmune related disease. The authors suggested the term “non-alcoholic duct destructive chronic pancreatitis” to encompass these histopathological changes.
Similar pancreatic lesions to those described above have been reported in two cases of primary sclerosing cholangitis, particularly a diffuse lymphoplasmacytic infiltrate, notable interstitial fibrosis and acinar atrophy.7 However, immunotyping of the lymphocytic population was not carried out.
In summary, the study by Ectors et al focuses on a novel pathological concept, that of non-alcoholic duct destructive chronic pancreatitis. It draws the clinician’s attention to a set of uncommon pancreatic lesions which seem to be unrelated to alcohol or to any of the other conventional causes of chronic pancreatitis in the West. From the pathologist’s viewpoint, it certainly provides a significant advance in the understanding of so called idiopathic chronic pancreatitis.
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