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Pancreatic Pathology Online
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Exocrine Pancreatic Tumours.
Ductal
adenocarcinoma accounts for about 80-90% of
malignant exocrine tumours.
Etiology:
Etiology is complex and probably multifocal, although
smoking and a
high intake of dietary fat seem important.
Familial causes are rare but pancreatic ductal
adenocarcinoma may occur in some families
with
history of
cancer.
Age and sex
:
Mostly seen over
50 years of age.
Male: female
ratio is 1.5 : 1.0
Sites and
clinical features:
1. Head
(two-thirds of the cases)- causes obstruction of the
biliary tract
with jaundice and occlusion of the main
pancreatic duct leading to obstructive
pancreatitis.
2. Tail, uncinate
process or in combined sites:
Patients present
with pain and weight loss or liver metastases
from an "occult"
primary.
Spread:
- Local
spread: depends on the location of the tumour
and include:
From head:
bile duct,
duodenum and retroperitoneum.
From tail:
peritoneum, stomach, colon, spleen and left adrenal.
- Lymphatic
spread:
To the Peri -pancreatic
lymph nodes ;
To
the regional lymph
nodes (in the hepatoduodenal ligament
up to the ciliac trunk) in about 50% of cases.
( "Juxta-regional
" - mainly para-aortic lymph nodes
in about 10% of cases).
- Blood-borne metastases:
To the liver, lungs, pleura and bone.
Gross features :
Head: Generally
"solid", poorly demarcated, hard, yellowish-
white to gray,
often about the size of 2-5 cm in diameter.
Hemorrhage,
necrosis, and cystic change is rare except in
very large
cancer.
Body or tail: Diffuse growth spreading in the parenchyma.
Average size is about 5-7 cm or more.
Pathological
staging (TNM classification ):
I - Based on the
size of the primary tumor:(pT1-pT4)
II - Presence or
absence of regional metastatic lymph nodes
(pN1a or pN1b),
if multiple lymph nodes are involved.
III - Distant
metastases (pM).
Microscopic features:
1. Well to
moderately differentiated tumours :
Consists of
tubular and glandular structures lined by
mucus-secreting columnar cells arranged in a
single regular
layer, but may show stratification and papillary projection.
There is a marked desmoplastic reaction, with formation of
dense fibrous
tissue.
2. Moderately and
poorly differentiated tumours:
Consists of poorly
formed glands with decreased mucus
secretion.
Pleomorphism and
mitotic figures are present.
Immunohistochemical
findings:
1. Antibodies to
cytokeratin 7, 8, 18, and 19.
2. Epithelial
Membrane Antigen (EMA)
3.
Carcinoembryonic Antigen (CEA)
4. DUPAN-2.
Ultrastructural findings:
The majority of
ductal adenocarcinomas show K-ras and
P53 mutations, which
differentiate it from mucinous cystic
tumours, acinar cell carcinomas, and
endocrine tumours,
all of which lack
these mutations.
Differential
diagnosis:
Chronic Pancreatitis
:
1. Usually
reveals remnants of lobules embedded in
fibrotic tissue.
2. Remaining
ducts may be dilated or atrophic.
3. Ductal
epithelium may be atrophic or hyperplastic.
4. Calcification
and proteinaceous plugs in the ducts are common.
Prognosis:
Death within 3
years - 90% of cases.
5-year survival
is 1 to 5%.
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