HISTO: Pancreas and gallbladder Flashcards by Kishan P

Pancreatic microanatomy

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What are the two types of tissue seen on histology in the pancreas?

Excorine

Endocrine

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What is acute pancreatitis?

Acute inflammation of the pancreas caused by aberrant release of pancreatic enzymes. Relatively common, incidence increasing.

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What are the causes of acute pancreatitis? What are the two most common causes.

Duct obstruction = Gall stones (50%), Trauma, Tumours

Metabolic/toxic = Alcohol (33%) (5% of alcoholics develop acute pancreatitis); Drugs (e.g. thiazides); Hypercalcaemia, Hyperlipidaemia

Poor blood supply = Shock, Hypothermia

Infection/ inflammation - Viruses (e.g. mumps)

Autoimmune

Idiopathic (15%)

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What are the two mechanisms of pathogenesis of acute pancreatitis?

Duct obstruction- due to gallstones and alcohol
Direct acinar injury - all other causes

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What is the pathogenesis of duct obstruction causing acute pancreatitis?

Gallstone stuck distal to where the common bile duct and pancreatic ducts join

—> reflux of bile up the pancreatic duct —> damage to acini and release of proenzymes which then become activated

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How does alcohol cause acute pancreatitis?

Alcohol –> spasm/oedema of Sphincter of Oddi + formation of a protein rich pancreatic fluid –> obstructs the pancreatic ducts

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What are the 3 pattens of injury in acute pancreatitis?

Periductal - necrosis of acinar cells near ducts (usually secondary to obstruction)

Perilobular – necrosis at the edges of the lobules (usually due to poor blood supply)

Panlobular – develops from 1. and 2.

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How do activated enzymes e.g. lipases, cause these patterns of injury?

Activated enzymes –> acinar necrosis –> enzyme release etc.

Ranges from stromal oedema, to haemorrhagic necrosis

e.g. Lipases –> fat necrosis (calcium ions bind to free fatty acids forming soaps which are seen as yellow white foci)

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What are the complications of acute pancreatitis?

Pancreatic : pseudocyst, abscess

Systemic: shock, hypoglycaemia, hypocalcaemia

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What is the prognosis for acute pancreatitis?

Overall mortality up to 50% for haemorrhagic pancreatitis (due to association with systemic shock)

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What is shown?

Yellow white foci when calcium ions bind to fatty acids forming soaps

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What is chronic pancreatitis? How common is it?

Relapsing or persistent, associated with acute pancreatitis in half of cases

Relatively uncommon

Mortality 3% per year

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What are the causes of chronic pancreatitis? What is the most common cause?

Metabolic/toxic = Alcohol (80%); Haemochromatosis

Duct obstruction = Gallstones; Abnormal pancreatic duct anatomy; Cystic fibrosis (“mucoviscoidosis”)

Tumours

Idiopathic Autoimmune

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What is the pathogenesis of chronic pancreatitis?

Same as for acute pancreatitis

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What is the pattern of injury seen in chronic pancreatitis?

Chronic inflammation with parenchymal fibrosis and loss of parenchyma

Duct strictures with calcified stones with secondary dilatations

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What are the complications of chronic pancreatitis?

Malabsorption
Diabetes mellitus
Pseudocyts
Carcinoma of the pancreas - chronic pancreatitis may be a risk factor for this

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What is shown?

Calcification - could be either acute or chronic

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What are the cells in the middle in this slide of chronic pancreatitis?

Rounded areas are endocrine cells which survive well - although there is a risk of diabetes over time

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What are pancreatic pseudocysts associated with?

Associated with acute and/ or chronic pancreatitis

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What are the characteristics of pancreatis pseudocysts?

Lined by fibrous tissue (no epithelial lining), contain fluid rich in pancreatic enzymes or necrotic material

Connect with pancreatic ducts

May resolve, compress adjacent structures, become infected or perforate

What is a characteristic of IgG4 related disease? What parts of the body may be affected?

Characterised by large numbers of IgG4 positive plasma cells.

May involve the pancreas, bile ducts and almost any other part of the body

What disease is represented here?

IgG4 related disease

What are 3 types of tumours of the pancreas?

Carcinomas

Ductal (85% of all neoplasms)
Acinar

Cystic neoplasms

Serous cystadenoma
Mucinous cystic neoplasm

Pancreatic neuroendocrine tumours (Islet cell tumours)

What is the most common type of pancreatic tumour?

Ductal carcinomas (85% of all)

What is the prognosis with ductal carcinoma in the pancreas?

* 5% of cancer deaths * Increasingly common with age, 2M: 1F * 5 year survival: 5%

What are 3 risk factors for pancreatic carcinomas?

* Smoking * BMI and dietary factors * Chronic pancreatitis * Diabetes

What mutations are common in pancreatic ductal carcinomas? How do these cancers arise?

Arise from dysplastic ductal lesions: * Pancreatic Intraductal Neoplasia (PanIN) * Intraducal Mucinous Papillary Neoplasm K-Ras mutations in 95% of cases

What is the macroscopic appearance of ductal carcinomas of the pancreas?

* Gritty and grey * Invades adjacent structures * Tumours in the head present earlier

What are the microscopic features of ductal carcinomas of the pancreas?

Adenocarcinomas: **mucin** secreting glands set in **desmoplastic stroma**

Where do most ductal carcinomas of the pancreas arise?

* Head (60%) * Body * Tail * Diffuse

Where do pancreatic ductal carcinomas spread to?

* Direct: Bile ducts, duodenum * Lymphatic: Lymph nodes * Blood: Liver * Serosa: Peritoneum Perineural?

What are the complications of pancreatic ductal carcinomas?

Complications are due to spread * Chronic pancreatitis * Venous thrombosis (“migratory thrombophlebitis”)

What are the two types of cystic tumours of the pancreas? What are their features?

Are made of **serous** or **mucinous** secreting epithelium (cf. ovarian tumours) Usually benign

What are the features of this pancreatic cystic tumour?

* Benign * Sharply demarcated * Does nt invade locally or distally

Are most pancreatic endocrine neoplasms secretory or non-secretory?

Non-secretory in most cases except for insulinomas

Give an example of a neuroendocrine marker which can be used to screen for pancreatic endocrine tumours?

Contain neuroendocrine markers e.g. chromogranin

What is a genetic cause of pancreatic endocrine neoplasms?

may be associated with the Multiple Endocrine Neoplasia (MEN) 1 syndrome

What is the problem with pancreatic endocrine tumours?

behaviour difficult to predict

What is the most common secretory tumour of the pancreas?

Insulinoma - derived from beta cells Commonest type of secretory tumour

How common is cholelithiasis?

20% of adults in the West

What are the risk factors for gall stones?

* Age and gender: increasing age, F\>M * Ethnic and geographic: e.g. Native Americans * Hereditary: e.g. disorders of bile metabolism * Drugs e.g. oral contraceptive * Acquired disorders e.g. rapid weight loss

What are the types of gall stones? How do they appear on imaging?

**Cholesterol** (\>_50% cholesterol_) = may be single, mostly radiolucent **Pigment** (contain _calcium_ salts of _unconjugated bilirubin)_ = multiple, mostly radio-opaque

What are the complications of gall stones?

* Bile duct obstruction * Acute and chronic cholecystitis * Gall bladder cancer * Pancreatitis

What is acute cholecytitis most associated with?

= acute inflammation ## Footnote **90% associated with gall stones**

What are the histopathological features of chronic cholecystitis?

= chronic inflammation 1. Fibrosis 2. Diverticula – Rokitansky-Aschoff sinuses 3. 90% contain gall stones

What is the thickness of a normal gall bladder wall?

2mm

What is this feature of chornic cholecystitis?