Category Archives: Pancreas

Serous microcystic adenoma

Serous microcystic adenoma

Gross Features

-    Most frequently occur in tail

-    Single, well-circumscribed slightly bosselated, round lesions with diameters ranging from 1-25 cm in greatest dimension (average, 6-10 cm)

-    Sponge-like and made up of numerous tiny cysts filled with serous fluid

-    Cysts range from 0.01-0.5 cm but can be up to 2 cm in diameter

-    Cysts are arranged around a centrally located, dense fibronodular core from which thin fibrous septae radiate to the periphery (central stellate scar)

Microscopic Features

-    Cyst pattern resembles that of a sponge on low power

-    Cysts contain proteinaceous fluid are lined by a single layer of cuboidal/flattened epithelial cells

-    Cellular cytoplasm is clear and only rarely eosinophilic and granular

-    Centrally located nuclei, round to oval in shape, uniform, with an inconspicuous nucleolus

-    PAS positive, PASD and Alcian blue negative

-    No mitoses or cytologic atypia

-    Central fibrous stellate core formed of hyalinised tissue with a few clusters of tiny cysts

•    Serous oligocystic adenoma

•    Serous cystadenocarcinoma

Posted in Pancreas | Tagged , , , , , , | Comments Off

Mucinous cystic neoplasms

Mucinous cystic neoplasms

Gross Features

-    Arise in the body/tail of the pancreas; present as painless, slow growing masses

-    Cysts are filled with thick, tenacious mucin

-    Neoplasms show no attachment to main pancreatic ducts

Microscopic Features

-    Cysts are lined by columnar mucinous epithelium with a dense stroma resembling ovarian stroma

-    Benign mucinous cystadenomas lack cytologic or architectural atypia

-    Borderline mucinous cystadenomas possess cytologic atypia and demonstrate cellular pseudostratification and pseudopapillary formation (architectural atypia) but do not invade the stroma

-    Mucinous cystadenocarcinomas demonstrate cytologic and architectural atypia with definite stromal invasion

Posted in Pancreas | Tagged , , , , | Comments Off

Intraductal Papillary Mucinous Neoplasms

Intraductal Papillary Mucinous Neoplasms

Gross Features

-    Arise in the head of the pancreas (males>females)

-    Cysts are filled with mucin

-    Neoplasm is connected to main pancreatic duct

Microscopic Features

-    Cysts are lined by columnar mucinous epithelium lacking a dense ovarian-type stroma

-    Benign mucinous cystadenomas lack cytologic or architectural atypia

-    Borderline mucinous cystadenomas possess cytologic atypia and demonstrate cellular pseudostratification and pseudopapillary formation (architectural atypia) but do not invade the stroma

-    Mucinous cystadenocarcinomas demonstrate cytologic and architectural atypia with definite stromal invasion

Posted in Pancreas | Tagged , , , , | Comments Off

Serous Pseudopapillary Tumor

Serous Pseudopapillary Tumor

Gross Features

-    Large, well-circumscribed masses with cystic and solid zones

-    Cystic spaces contain hemorrhagic debris

Histology and Microscopic Features

-    Cells grow as sheets or as papillary projections

Posted in Pancreas | Tagged , , , | Comments Off

Pancreatic Cystic Lesions

Pancreatic Cystic Lesions

Cystic lesions of the pancreas

Classification

•    Non-neoplastic cysts
-    Pseudocysts
-    Congenital cysts
•    Neoplastic cysts
o    Serous cystic neoplasms
-    Serous microcystic adenoma
-    Serous oligocystic adenoma
-    Serous cystadenocarcinoma
o    Mucinous cystic neoplasms
-    Benign
-    Borderline
-    Malignant
o    Intraductal papillary mucinous neoplasms
-    Benign
-    Borderline
-    Malignant
o    Solid-pseudopapillary tumor

Posted in Pancreas | Tagged , , , , , , , , | Comments Off

Acute Pancreatitis

Acute pancreatitis

Causes of Acute Pancreatitis

•    Metabolic
o    Alcoholism
o    Hyperlipoproteinemia
o    Hypercalcemia
o    Drugs (eg. thiazide diuretics)
•    Mechanical
o    Trauma
o    Gallstones
o    Iatrogenic injury (perioperative injury,  endoscopic procedures with dye injection)
•    Vascular
o    Shock
o    Atheroembolism
o    Polyarteritis nodosa
•    Infectious
o    Mumps
o    Coxsackie virus
o    Mycoplasma pneumoniae
•    Idiopathic/genetic
o    Hereditary pancreatitis (mutations in cationic trypsinogen gene)
o    Mutations in SPINK1 (serine protease inhibitor Kazal type 1)

Gross features

•    Chalky-white fat necrosis
•    Areas of hemorrhage within pancreatic parenchyma

Pathogenesis

•    Due to autodigestion of pancreatic substance due to inappropriately activated pancreatic enzymes
•    Activated enzymes (trypsin, lipase, phospholipase, elastase) cause disintegration of fat cells, and damage blood vessel walls.
•    Trypsin converts prekallikrein to its activated form and also activates Hagemann factor.  This activates the kinin cascade and the clotting and complement cascades which in turn leads to increased inflammation and thrombosis of small vessels (causing congestion and rupture of already weakened vessels).
•    Three proposed mechanisms by which pancreatic enzymes are inappropriately activated:
o    Pancreatic duct obstruction
-   Increase in intrapancreatic ductal pressure, causes production of enzyme-rich interstitial fluid.  Lipase secreted in active form injures fat cells causing local fat necrosis.  Injured tissues, myofibroblasts, and leukocytes secrete cytokines causing local inflammation and promoting interstitial edema (which in turn compromises blood flow, causing ischemic injury to acinar cells).
o    Primary acinar cell injury
o    Defective intracellular transport of proenzymes within acinar cells
-    May occur with pancreatic duct obstruction or exposure to alcohol

Complications

•    ARDS
•    DIC
•    Shock
•    ATN
•    Pancreatic abscess
•    Pancreatic pseudocyst
•    Gram negative infection of necrotic debris in acute necrotizing pancreatitis

References: Robbins & Cotran Pathologic Basis of Disease, Seventh Edition
by: Vinay Kumar, Nelso Fausto, Abul Abbas

Posted in Pancreas | Tagged , , , | Comments Off

Pancreatitis

Pancreatitis

Complications of acute pancreatitis

- systemic organ failure – shock, ARDS, ARF
-DIC
- pancreatic abscess
- pancreatic pseudocyst
-duodenal obstruction

Five causes

- alcohol
- gallstones
- post-ERCP
- infections
- trauma

 Pathogenesis

- inappropriate activation of trypsin which in turn leads to activation of other proenzymes and activation of the kinin system leading to inflammation and thrombosis.

Mechanisms of pancreatic enzyme activation

- pancreatic duct obstruction – ie. gallstones
- primary acinar cell injury – ie, viral damage ( mumps), drugs, trauma or ischemia
- defective intracellular transport of proenzymes- ie. alcohol, hereditary pancreatitis

Gross findings

- enlarged and soft pancreas
- chalky white foci of fat necrosis
- hemorrhage in more severe cases

Microscopy

- edema
- acute inflammation
- fat necrosis

Clinical and laboratory manifestations

- epigastric pain that often radiates to back
- elevated serum amylase
- diffuse pancreatic enlargement on imaging

Posted in Pancreas | Tagged , , , | Comments Off

Pancreas Hereditary Syndromes

Pancreas Hereditary Syndromes

Preneoplastic lesion

PanIN – pancreatic intraepithelial neoplasia

2 herditry familial syndromes associated with pancreatic cancers:

HNPCC –MSH2 and MLH1

BRCA2

FAMM ( familial atypical multiple melanoma syndrome)  – p16

Hereditary pancreatitis ( loss of site on trypsin for it’s own autodestruction)  – PRSS1

Peutz –Jeger  =STK11/LKB

Posted in Pancreas | Comments Off

Pancreas Cancer Mutations

Pancreas Cancer Mutations

- most common mutation found in cancers of the pancreas include:

KRAS  – in >90% of  pancreatic cancers

Posted in Pancreas | Comments Off

Pseudocyst

Pancreatic Pseudocyst

What is it?

- localized collection necrotic material rich in pancreatic enzymes, usually following acute pancreatitis which becomes walled off by  granulation tissue or fibrous tissue

Management

Supportive care

Some may require surgical drainage

Posted in Pancreas | Tagged , , | Comments Off