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