GI Pathology Note - Lecture notes 4 PDF

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01.COMMON PATHOLOGIES AFFECTING THE GISYSTEM1. LIVER ANATOMYA. 2 principal lobes (right and left), separated by Falciform ligament (fold of parietal peritoneum) B. Free border of falciform is called the Ligamentum teres (remnant of the umbilical vein) C. Right and left coronary ligaments suspend liv...

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01.03.2019

COMMON PATHOLOGIES AFFECTING THE GI SYSTEM 1. LIVER ANATOMY A. 2 principal lobes (right and left), separated by Falciform ligament (fold of parietal peritoneum) B. Free border of falciform is called the Ligamentum teres (remnant of the umbilical vein) C. Right and left coronary ligaments suspend liver from diaphragm D. Left and right triangular ligaments suspend posterior aspects of liver from diaphragm

2. LIVER HISTOLOGY A. Liver lobes made up of functional units called Lobules B. Lobules consist of hexagonal hepatocytes around a central vein C. Instead of capillaries the liver has large endothelial lined spaces called sinusoids D. There are fixed phagocytes in sinusoids called Kupffer (stellate reticuloendothelial) cells – destroys waste products E. Bile is secreted by hepatocytes F.

Bile drains into canaliculi → ductules → ducts → left and right hepatic ducts

3. LIVER BLOOD SUPPLY

4. LIVER FUNCTIONS A. Secretes Bile (emulsifies fats) B. Carbohydrate metabolism (Gluconeogenesis – Glycogenolysis; fatty acid catabolism) C. Lipid metabolism D. Protein metabolism (deamination; synthesises plasma proteins) E. Processes and excretes drugs, hormones (oestrogen), bilirubin F.

Stores vitamins (A, B12, D, E, K)

G. Activates Vitamin D

5. ACUTE LIVER INJURY To get started right away, just tap any placeholder text (such as this) and start typing. A. Aetiology

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i.

Autoimmune (PBC)

ii.

Secondary to biliary obstruction

iii.

Viruses (Hep A, B or C)

iv.

Drugs (Alcohol, drugs)

v.

Jaundice (bilirubin retention > 3mg/dL)

6. JAUNDICE

7. INVESTIGATIONS FOR JAUNDICE To get started right away, just tap any placeholder text (such as this) and start typing. A. Haematological and Biochemical tests i.

FBC

ii.

LFTs (Bilirubin, ALK, ALT, GGT)

iii.

Albumin

B.

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Non-invasive imaging i.

USS (Liver, Gallbladder, Bile ducts)

ii.

CT (Parenchymal pancreas, liver, gallbladder disease – distant disease)

iii.

MRI (bile duct system, pancreas)

8. TREATMENT OF JAUNDICE A. Depends on: i.

Underlying aetiology

ii.

Disease stage

iii.

What we can offer the patient

iv.

What the patient wants!

9. CIRRHOSIS A. Disruption of liver architecture with fibrous tissue B. Aetiology: i.

Alcoholic liver disease

ii.

Chronic Hepatitis B and C

iii.

Non-alcoholic steatohepatitis (NASH) – associated with Type 2 DM and obesity

10.

PORTAL HYPERTENSION To get started right away, just tap any placeholder text (such as this) and start typing. A. Elevated portal pressure > 15mmHg B. Causes

4

i.

Inflow/Outflow obstruction

ii.

Pre-hepatic – Vein thrombosis, extrinsic vein compression

iii.

Intrahepatic – Cirrhosis, fibrosis

iv.

Post-hepatic – Veno-occlusive disease, Budd-Chiari syndrome (hepatic vein thrombosis)

11.

GALLBLADDER A. 10cm long, pear shaped sac on posterior liver surface B. Stores bile (bile salts – emulsifies fats, bile acid, pigments, cholesterol, lecithin)

12.

GALLBLADDER DISEASE Gallstones A. Associations - 4Fs (Fat, female, fertile, forties) B. Pathogenesis

C. 5

i.

Cholesterol – imbalance between cholesterol and phospholipids (Western World)

ii.

Pigment – Excessive bile pigments or chronic haemolytic disorders Presentation

i.

Biliary colic – RUQ pain with radiation to tip of scapula

ii.

Acute cholecystitis – RUQ pain with systemic sepsis symptoms

iii.

Mucocele/Empyema – sterile/infected contents

iv.

Perforated – very poorly patient!

v.

Fistula – connection between GB and small bowel – obstruction

vi.

13.

Chronic cholecystitis – shrunken, thick walled GB

GALLSTONE MANAGEMENT A. Asymptomatic – no treatment required B. Acute / Chronic gallstone cholecystitis – IV fluids, Antibiotics, Surgery C. Gallstone ileus (GS erodes into small bowel – diagnosed at Surgery for small bowel obstruction) D. Common Bile duct stones – removed via Endoscopic Retrograde Pancreatography

14.

PANCREAS A. Retroperitoneal 15cm structure in the epigastrium B. Mixed gland i.

Exocrine: glandular epithelium – acinar cells (99%) 1. Secretes Pancreatic juice a. Amylase b. Trypsin, Chymotrypsin, Carboxypeptidase, Elastase c. Lipase d. Ribonuclease, Deoxyribonuclease

ii.

Endocrine: Islets of Langerhans (1%) 1. Secretes Glucagon, Insulin, Somatostatin, Pancreatic Polypeptide

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PANCREATITIS A. Mixed Pancreatic inflammation B. Aetiology i.

Gallstones

ii.

Alcohol

iii.

Idiopathic

C. Presentation – epigastric pain radiating to the back i. 6

Tachycardia, hypotension, pyrexia

ii.

Blood stained exudate tracking into abdominal wall 1. Grey Turner’s sign (flank) 2. Cullen’s sign (periumbilical)

D. investigations i.

FBC, LFTs, Amylase (>1000IU/ml – diagnostic)

ii.

AXR, CXR, USS (gallstone disease), CT (pancreas), MRCP (stones in common bile duct)

E. Management i.

Intensive monitoring – p, BP, T, oxygen saturation, urine output

ii.

Analgesia

iii.

Supportive IV Fluids – 3rd space losses

iv.

Pancreas imaging – CT

v.

ERCP – previously described to remove stones for CBD

vi.

Laparoscopic Cholecystectomy – remove Gallstones

F.

Complications of Pancreatitis i.

Pancreatic Pseudocyst (fluid filled cavity lacking a wall)

ii.

Pancreatic necrosis (acinar death)

iii.

Acute Respiratory Distress syndrome (lung injury)

iv.

Renal failure (dehydration)

16.

LARGE BOWEL A. 1.5m long, structurally caecum, colon, rectum, anal canal B. Functions:

17.

i.

Haustral churning – mass peristalsis

ii.

Bacteria produce B vitamins and Vitamin K

iii.

Water and Ion absorption

iv.

Defaecation (emptying of rectum)

LARGE BOWEL PATHOLOGY A. Acute Appendicitis B. Inflammatory Bowel Disease C. Diverticulosis D. Volvulus E. Colon Cancer F. 7

Ischaemic colitis

G. Colonic obstruction

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ACUTE APPENDICTIS A. Appendiceal inflammation B. Approximately 60% retrocecal C. Appendix luminal obstruction with faecolith or lymphoid inflammation D. Blood supply is an end artery (appendicular a.) → gangrene → perforation E. Presentation – central abdominal pain radiating to RIF i. F.

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Tachycardia, hypotension, mild grade pyrexia, anorexia Management – Analgesia, IV fluids, IV antibiotics, Appendicectomy (Open vs Laparoscopic)

19.

INFLAMMATORY BOWEL DISEASE A. Ulcerative colitis (UC) i.

Involves rectum to proximal colon

ii.

Unknown aetiology – assoc. with HLA-B27, non-smokers, and F>M

iii.

Macroscopically – mucosal ulceration, pseudoplyps

iv.

Microscopically – crypt disruption and abscess formation

v.

Presentation – increasing severity of loose, bloody stools with abdominal pain and systemic features (weight loss, pyrexia)

vi.

Investigations – Bloods, Colonoscopy, CT imaging, stool samples (other causes)

vii.

Management: 1. Medical – Topical or systemic steroids; immunosuppressants 2. Surgery - Colectomy

B. Crohn’s i.

Transmural granulomatous process affecting any part of alimentary canal

ii.

Unknown aetiology – M>F, smokers, younger patients

iii.

Macroscopically – erythematous, skip lesions

iv.

Microscopically – granulomas

v.

Presentation – Abdominal pain, weight loss, bloody diarrhoea, perianal problems

vi.

Investigations – Bloods, Upper and Lower GI endoscopy, CT imaging

vii.

Management – Steroids, immunosuppressants, resection surgery

C. Diverticulosis i.

Mucosal herniation between taenia coli

ii.

>40M with poor fibre and fluid intake

iii.

Presentation depends on complications: 1. Diverticulosis – altered bowel habit 2. Diverticulitis – LIF pain, pyrexia 3. Perforation – peritonitis 4. Fistula – cystitis, faecal discharge 5. Haemorrhage – PR bleeding

iv.

Management: 1. High fibre diet, IV fluids, IV antibiotics 2. CT guided drainage of collections 3. Surgery

D. Volvulus

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i.

Twisting of large bowel along its mesentery

ii.

Blood supply affected causing ischaemia & perforation

iii.

Can cause large bowel obstruction

iv.

Sigmoid volvulus

1. Elderly patients with chronic constipation 2. Present with colicky abdominal pain, absolute constipation and abdominal distension 3. Management – decompression with endoscopy: resection surgery v.

Caecal volvulus 1. Congenital abnormality of long caecal mesentery 2. Closed loop obstruction occurs 3. Blood supply becomes compensated 4. Management: a. Resuscitation b. Resectional surgery

E. Colonic cancer i.

3rd commonest cancer, M = F, low fibre diet/red meat associated

ii.

Risk factors – Familial polyposis coli, UC

iii.

Pathologically adenocarcinomas: 1. Diffuse 2. Ulcerative 3. Annular 4. Polypoidal

iv.

Classification (Modified Dukes’)

v.

Clinical presentations

vi.

Investigations and management 1. Clinical examination 2. Bloods, CXR, AXR, CT, MRI pelvis (rectal disease) 3. Colonoscopy 4. Multi-disciplinary team meeting (Oncologists, Surgeons, Pathologists, radiologists) 5. Radiotherapy, Chemotherapy, Surgery (Curative, Palliative)

F.

Ischaemic colitis i.

Atherosclerosis, smokers, CV disease, AF

ii.

Presentation

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1. LIF pain with bloody diarrhoea 2. Occurs at watershed area (related to poor blood supply here secondary to anastomosis between midgut and hindgut structures) iii.

Diagnosis 1. CT imaging

iv.

Management 1. Resuscitation (IV fluids, IV Antibiotics) 2. Very rarely resectional surgery

G. Colonic obstruction i.

Common cause for surgical admission

ii.

Presentation: 1. Colicky abdominal pain 2. Abdominal distension 3. Constipation 4. Early vs late vomiting

iii.

Colonic obstruction management 1. Investigations a. Bloods, AXR, CXR, CT imaging 2. Management a. Resuscitation – IV fluids b. Resectional surgery

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