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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 - 1 to 5%.
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