Morphological study of 391 cases of exocrine pancreatic tumours with special reference to the classification of exocrine pancreatic carcinoma.

Three hundred and ninety-one cases of primary pancreatic tumours, excluding endocrine tumours, were studied histologically. Carcinoma of the exocrine pancreas formed the largest group (98.5 per cent), benign tumours (1.25 per cent) and other malignant tumours (0.25 per cent) formed the remainder. Ductal adenocarcinoma was the commonest type and was divided into four sub-types, papillary, well, moderately and poorly differentiated duct adenocarcinoma. The moderately and poorly differentiated tumours were the commonest types. Papillary carcinoma was separated from the well differentiated tumours by its different morphological appearances and was found to exhibit different behaviour. Other special morphological types of pancreatic carcinoma, pleomorphic, mucinous, adenosquamous, acinar, microadenocarcinoma, cystadenocarcinoma and oncocytic carcinoma were also represented. Benign microcystadenomata (four cases) were considered because of their interesting morphological features and their significance in the differential diagnosis of carcinoma. Based on the morphology and behaviour of these 391 tumours, the classification of pancreatic carcinoma is discussed and some rare types are compared with previously reported cases and discussed.