GI Tutorial

General Structure

• Mucosa– Epithelium– Lamina Propria– Muscularis Mucosa

• Submucosa– Connective tissue, blood vessels, nerve plexus

• Muscularis propria• Serosa & subserosa

– Fat, connective tissue, blood vessels– Lined by peritoneum in areas

Structure and Function

• Tubular structure– Complications:

• Bleed – Haemorrhage• Burst – Perforation• Block – Obstruction• Fistula formation

• Digestive and Absorptive function– Complications

• Malabsorption– Total– Specific: Vit B12, fatty acids, proteins

• Diarrhoea

GI Tumours• Tumour structure

– Exophytic = nodule / polyp– Diffuse infiltrative = spread thru wall +/- stricture– Endophytic = ulcer / excavation

• Microscopy– Adenocarcinoma

• Signet ring carcinoma (stomach), typical adenoca (all areas)

– Squamous cell carcinoma• Oesophagus, Anus, Pharynx, Oral Cavity

– Rarer tumours• Carcinoid (anywhere, commonly appendix)• Sarcoma (leiomyosarcoma / gastrointestinal stromal tumour)• Lymphoma• Melanoma (oesophagus)

GI Tumours

• Pathogenesis = enviromental & host factors– Enviromental factors

• Drugs– Smoking

– Alcohol

• Diet– Nitrosamines, Vit deficiency (Oesophagus)

– Preservatives, Lack of fresh fruit/veg (Stomach)

– Excess intake/red meat/refined carbs, low fibre (Colon)

GI Tumours

• Pathogenesis = enviromental & host factors– Host factors

• Predisposing inherited conditions– FAP, Gardner syndrome, HNPCC (Colon ca)

• Predisposing inflammatory conditions– Barretts oesophagus (oesophagus)– Autoimmune / HLO gastritis (stomach)– Coeliac disease (SI)– Ulcerative colitis (colon)

• Family history (especially colon ca)

Approach to GI Tumour Questions

• Epidemiology– Male / female, age, race, geographic distribution

• Pathogenesis– enviromental: drugs, diet, other

– host: inherited / inflammatory conditions, family hx

– Sequence of events:• Inflammation metaplasia dysplasia invasion

• Sequence of mutations (adenoma carcinoma sequence in colon)

Approach to GI Tumour Questions

• Morphology– Gross:

• Location– Upper/mid/distal oesophagus, pylorus/cardia/fundus, duodenum/

ampulla/jejunum/ileum, caecum/asc/trans/des/sigmoid/rectum

• Appearance– Exophytic, infiltrative, endophytic

– Microscopy• Adenocarcinoma (+/- signet ring), squamous, other

– Spread• Local lymph nodes, liver, lungs, ovaries

Approach to GI Tumour Questions

• Clinical– Presentation

• Weight loss, anorexia, altered bowel habit, pain• Obstruction

– dysphagia, vomiting, abdo distension with constipation• GI haemorrhage – chronic : anaemia

– acute: haemoptysis, meleana, collapse

• Metastatic disease – hepatomegaly, ascites, lung lesions

– Prognosis / Staging– Complications:

• Haemorrhage, Perforation, Obstruction, Fistula formation• Local spread: compression/invasion of adjacent organs• Distant mets

SI obstruction