Toward a new classification of chronic pancreatitis

Guidelines on the histopathology of chronic pancreatitis. Recommendations from the working group for the international consensus guidelines for chronic pancreatitis in collaboration with the International Association of Pancreatology, the American Pancreatic Association, the Japan Pancreas Society, and the European Pancreatic Club

BACKGROUND

Chronic pancreatitis is a complex multifactorial fibro-inflammatory disease. Consensus guidelines are needed for the histopathological evaluation of non-autoimmune chronic pancreatitis (CP).

METHODS

An international working group with experts on the histopathology of CP evaluated 15 statements generated from evidence on seven key clinically relevant questions. The Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach was used to evaluate the level of evidence available for each statement. To determine the level of agreement, the working group voted on the statements for strength of agreement, using a nine-point Likert scale, and Cronbach's alpha reliability coefficients were calculated.

RESULTS

Strong consensus was obtained for 12 statements relating to all seven key questions including that: the cardinal features of CP are the triad of fibrosis, loss of acinar tissue and duct changes; there are no unique histopathological features that distinguish the different aetiologies of CP; clinical history and laboratory investigations, including genetic testing, are important in establishing the aetiology of CP; there is no reproducible and universally accepted histological grading system for assessing severity of CP, although classification as "mild", "moderate" and "severe" is usually applied; scoring systems for fibrosis are not validated for clinical use; asymptomatic fibrosis is a common finding associated with ageing, and not necessarily evidence of CP; there are no obvious diagnostic macroscopic features of early CP; histopathology is not the gold standard for the diagnosis of CP; and cytology alone is not a reliable method for the diagnosis of CP.

CONCLUSIONS

Cardinal histopathological features of CP are well-defined and internationally accepted and pathological assessment is relevant for the purpose of differential diagnosis with other pancreatic diseases, especially cancer. However, a reliable diagnosis of CP requires integration of clinical, laboratory and imaging features and cannot be made by histology alone.

Pancreatitis: A Forensic Perspective

Among the numerous etiologies of acute and chronic pancreatitis, several underlying causes (e.g., chronic alcohol abuse, trauma, medical therapy) may result in a death that is reportable to the medical examiner/coroner. As such, forensic pathologists are likely to encounter pancreatitis at autopsy and therefore must be familiar with its etiologies, mechanisms of death, autopsy findings, and medicolegal investigation. This review will focus on the aspects of pancreatitis that may be useful to forensic pathologists in their daily practice. This includes determining if acute or chronic pancreatitis caused or contributed to death as well as determining the etiologically specific proximate cause of death. Current theories of how these various processes result in inflammation of the pancreas are reviewed.

[Autoimmune pancreatitis]

Autoimmune pancreatitis has been established as a special entity of pancreatitis. It is an enigmatic disease since it is adding an autoimmune etiology to the existing causes of pancreatitis. Morphological hallmarks of the disease are narrowing of the pancreatic duct system and the bile duct by periductal lymphoplasmocytic inflammation. This results in many cases in obstructive jaundice due to a mass-forming lesion in the pancreatic head mimicking pancreatic ductal adenocarcinoma. Therefore, patients will frequently undergo surgery. Histopathologically, the disease can be diagnosed by IgG4-positive plasma cells. Serologically, patients may present with elevated serum IgG and IgG4 levels. Other autoantibodies are also described. Association with other autoimmune manifestations in a wide range of organs is frequent. Autoimmune pancreatitis will respond to steroid treatment, which is of specific importance because pancreatic cancer is one of its clinical differential diagnoses. It is important to positively diagnose autoimmune pancreatitis, especially if the bile ducts are affected, since cholangitis may be or become a prominent problem before or after surgery.