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Pancreatic Pathology Online
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.
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Histological features of pancreatic duct
obstruction:
Preservation of lobular architecture
Dilatation of acini
Acinoductular transformation
Progressive loss of exocrine elements
Residual loss of ‘lobular’ islets
Interlobular ductal papillary hyperplasia
No cytological atypia.
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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.
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Histological features of pancreatic adenocarcinoma :
Nuclear pleomorphism
Desmoplastic stroma
‘Random ducts' in fibrous tissue
‘Angular ducts’
Papillary projections
Pancreatic obstruction
Prominent nucleolation
of tumour cells
Obvious mitotic
activity
Perineural infiltration
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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.
Chronic Pancreatitis
;
Autoimmune Pancreatitis
;
Herpes Simplex Pancreatitis
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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