Pancreatic Pathology Online
Contrasting histological features of the obstructed pancreas and pancreatic adenocarcinoma
Dr Sampurna Roy MD July 2016
The obstructed pancreas can be recognized at a low magnification when the lobular nature of the obstructed parenchyma can be identified.
This is similar to diagnosing sclerosing adenosis in the breast.
Within the pancreatic lobules there is acinoductular transformation (dilatation of acini with loss of zymogen granules) and later marked exocrine atrophy with preservation of islets, which remain in lobules.
Large interlobular ducts may show papillary hyperplasia but will not show cellular atypia.
By contrast, at low magnification a pancreatic adenocarcinoma shows no lobular architecture, the duct-like structures being apparently present in the fibrous tissue in a random manner.
Neoplastic ducts tend to be angular, and cytological features of malignancy are common.
Since tumours frequently obstruct large pancreatic ducts, biopsies where both malignancy and obstructive features are present are quite common and recognition of the latter helps in the diagnosis of the tumour since the cytological appearances are usually obvious.
Confusion can occur when malignant ducts invade the obstructed areas of the pancreas but knowledge that this does occur should help in solving the diagnostic problem.
In chronic calcifying pancreatitis lobules at various stages of obstruction , fibrosis and duct inflammation all occur but the basic anatomy of the pancreas is preserved.
A random distribution of small ducts within the fibrous tissue is not see.
When only duct obstruction is seen on a needle biopsy, a positive diagnosis of chronic calcifying pancreatitis is still difficult because the obstruction could be secondary to a tumour which has been 'missed' by the biopsy.
Careful clinicopathological correlation is required.
In summary, most biopsied pancreatic carcinomas can be diagnosed at a low magnification by observing the distribution of the duct structures and lobules.
Higher magnification is used to confirm the diagnosis cytologically.
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