Gastrointestinal Tract for NEET PG Pathology: Oral and Oesophageal Cancer, Peptic Ulcer, Crohn vs UC, Coeliac, Colorectal Cancer

Start Here

🎯 Exam priority: High. Expect: Crohn vs ulcerative colitis, oesophageal SCC vs adenocarcinoma by site, linitis plastica, peptic ulcer pain patterns, coeliac serology, right- vs left-sided colon cancer, hereditary colon cancer syndromes and GIST.

CBME mapping: PA 23.1–23.9. Barrett metaplasia is in article 1; FAP and the adenoma-carcinoma sequence in article 4.

Crohn disease vs ulcerative colitis, and GI cancers. Drawn by TrackNation.

Mouth, Oesophagus and Stomach

• Oral SCC: over 95% of patients use tobacco, alcohol or both. Lesions appear as leukoplakia or erythroplakia, often indurated with a rolled border; floor of mouth and lateral/ventral tongue.

• Oesophageal cancer: SCC in the upper two-thirds (alcohol, tobacco; also achalasia, lye strictures, Plummer-Vinson webs); adenocarcinoma in the lower third (Barrett oesophagus from reflux, obesity). Progressive dysphagia and weight loss.

• Peptic ulcer: H. pylori and NSAIDs break mucosal defence. Duodenal ulcer pain is absent on waking, appears mid-morning, is relieved by food and returns 2–3 hours after meals. Rarely gastrinoma (Zollinger-Ellison).

• Stomach cancer: adenocarcinoma is 95%. Risk: H. pylori with intestinal metaplasia, autoimmune atrophic gastritis, smoking, polyps. Linitis plastica: diffuse infiltration with fibrosis — a rigid "leather bottle" stomach. Symptoms appear late.

Intestine

• Crohn disease: transmural, any part of the gut (usually distal ileum and colon) with skip areas; aphthous ulcers become deep ulcers with a cobblestone pattern; non-caseating granulomas are pathognomonic when seen but often absent; abscesses, fistulas, obstruction.

• Ulcerative colitis: mucosal, starts in the rectum and extends up; bloody diarrhoea; pseudopolyps; no fistulas or abscesses; raised colon cancer risk; raised ALP and GGT suggest primary sclerosing cholangitis; megacolon = transverse colon > 6 cm.

• Coeliac disease: gluten intolerance → villous atrophy and malabsorption. tTG-IgA and endomysial IgA are > 90% sensitive and specific; absence of HLA-DQ2/DQ8 effectively rules it out. Tropical sprue (southern India, Caribbean, South-East Asia): malabsorption with megaloblastic anaemia; tetracycline plus folate for 6 months. Whipple disease: Tropheryma whipplei — arthritis, weight loss, abdominal pain, diarrhoea.

• Appendicitis: luminal obstruction (usually lymphoid hyperplasia; sometimes faecolith, foreign body, tumour, worms) → distension, bacterial overgrowth, ischaemia; untreated → gangrene and perforation.

• Colorectal cancer: arises in adenomatous polyps; about 20% have an inherited component (FAP, Lynch, Peutz-Jeghers, juvenile and MUTYH polyposis); ulcerative colitis raises risk. Right-sided tumours bleed (anaemia); left-sided obstruct. CEA is raised in only about a third. GIST: C-KIT (sometimes PDGFRA) mutation; about half in the stomach.

Traps the Examiner Sets

• Upper oesophagus = SCC; lower = adenocarcinoma (Barrett).

• Crohn = transmural, skip, granulomas, fistulas; UC = mucosal, continuous from rectum, pseudopolyps.

• Right colon cancer → anaemia; left → obstruction.

• Linitis plastica = leather-bottle stomach.

• Duodenal ulcer pain is relieved by food.

Memory Hooks & Shortcuts

Shortcuts to lock in this article's numbers and lists. Each one only re-packages facts proven above.

• 🧠 Squamous on top, Adeno at the bottom — oesophageal cancer by site

• 🧠 Crohn's: Cobblestones, Granulomas, Skips, Fistulas — goes through all layers — Crohn features

• 🧠 UC: Up from the rectum, Continuous, mucosa only — UC features

• 🧠 Right Red (bleeds), Left Locks (obstructs) — colon cancer sides

• 🧠 Duodenal Delights in Dinner (food relieves) — duodenal ulcer pain

• 🧠 KIT keeps GIST — GIST mutation

Rapid-Revision Cards

• Oral SCC

  > 95% tobacco/alcohol; leukoplakia, erythroplakia; lateral tongue.

• Oesophageal cancer by site

  Upper 2/3 SCC; lower 1/3 adenocarcinoma.

• SCC vs adeno risks

  Alcohol, tobacco vs Barrett, reflux, obesity.

• Peptic ulcer causes

  H. pylori, NSAIDs; rarely gastrinoma.

• Duodenal ulcer pain

  Mid-morning, relieved by food, back 2–3 h later.

• Gastric cancer

  Adenocarcinoma 95%; H. pylori + metaplasia; atrophic gastritis.

• Linitis plastica

  Leather-bottle stomach.

• Crohn

  Transmural, skip areas, cobblestones, granulomas, fistulas.

• UC

  Mucosal, from rectum, pseudopolyps, no fistulas.

• UC + high ALP/GGT

  Primary sclerosing cholangitis.

• Megacolon

  Transverse colon > 6 cm.

• Coeliac tests

  tTG-IgA, EMA > 90%; no DQ2/DQ8 rules out.

• Tropical sprue

  S India; megaloblastic anaemia; tetracycline + folate.

• Whipple

  Tropheryma whipplei; arthritis, weight loss.

• Appendicitis

  Lymphoid hyperplasia blocks lumen.

• Colon cancer sides

  Right bleeds; left obstructs.

• CRC origin

  Adenomatous polyps; 20% inherited.

• CEA in colon cancer

  ~34% raised; not for screening.

• GIST

  C-KIT (or PDGFRA); stomach ~51%.

Sources

Facts in this article were checked against these documents.

• MSD Manual Professional: Oral Squamous Cell Carcinoma; Esophageal Cancer; Stomach Cancer; Colorectal Cancer; GISTs — Merck & Co. (MSD Manuals), reviewed 2025–26 (link)

• MSD Manual Professional: Peptic Ulcer Disease; Crohn Disease; Ulcerative Colitis; Celiac Disease; Tropical Sprue; Whipple Disease; Appendicitis — Merck & Co. (MSD Manuals), reviewed 2025–26 (link)

• Competency Based Undergraduate Curriculum, Pathology (PA 23) — National Medical Commission, 2024

Test Yourself: Practice Questions

Thirty questions in NEET PG style, most of them clinical vignettes.

Practice Questions (NEET PG pattern)

Original questions written in the style of the exam: +4 for a correct answer, −1 for a wrong one. Every answer was checked against the sources listed above. NEET PG papers are not published by NBEMS, so these are not past-paper questions.

Q1. A man who smokes and drinks heavily has a firm ulcerated lesion with a rolled border on the lateral tongue. The likely diagnosis is

• (a) aphthous ulcer

• (b) oral squamous cell carcinoma

• (c) lichen planus

• (d) oral candidiasis

Q2. Leukoplakia and erythroplakia in the mouth are recognised presentations of

• (a) oral squamous cell carcinoma (leukoplakia, erythroplakia)

• (b) vitamin C deficiency

• (c) measles

• (d) herpes simplex

Q3. A smoker and drinker has progressive dysphagia; biopsy of a mid-oesophageal mass is most likely

• (a) squamous cell carcinoma

• (b) GIST

• (c) lymphoma

• (d) adenocarcinoma

Q4. A man with years of reflux and Barrett oesophagus develops a cancer at the gastro-oesophageal junction. It is most likely

• (a) leiomyoma

• (b) adenocarcinoma

• (c) squamous cell carcinoma

• (d) small cell carcinoma

Q5. Which is a recognised risk factor for oesophageal cancer listed by MSD?

• (a) hepatitis B

• (b) lye ingestion with stricture

• (c) H. pylori eradication

• (d) vitamin D excess

Q6. The two main factors that disrupt gastroduodenal mucosal defence in peptic ulcer disease are

• (a) stress and spicy food

• (b) H. pylori and NSAIDs

• (c) alcohol and coffee

• (d) smoking and milk

Q7. Epigastric pain that is absent on waking, starts mid-morning, is relieved by food and returns 2–3 hours after meals suggests

• (a) duodenal ulcer

• (b) pancreatitis

• (c) biliary colic

• (d) gastric cancer

Q8. A patient has multiple refractory peptic ulcers from very high gastrin levels. The cause is

• (a) pernicious anaemia

• (b) H. pylori only

• (c) NSAID use

• (d) gastrinoma (Zollinger-Ellison syndrome)

Q9. The commonest malignant tumour of the stomach is

• (a) leiomyosarcoma

• (b) adenocarcinoma (95%)

• (c) lymphoma

• (d) GIST

Q10. Endoscopy shows a rigid, thick-walled stomach; biopsy shows tumour infiltrating the wall with fibrosis. This is

• (a) gastric ulcer

• (b) Ménétrier disease

• (c) linitis plastica (leather-bottle stomach)

• (d) GIST

Q11. A recognised risk factor for gastric adenocarcinoma is

• (a) hepatitis C

• (b) H. pylori with extensive intestinal metaplasia

• (c) coeliac disease

• (d) duodenal ulcer

Q12. A patient has diarrhoea, abdominal pain and an enteric fistula; diseased bowel segments are sharply separated from normal bowel. The likely diagnosis is

• (a) irritable bowel syndrome

• (b) ulcerative colitis

• (c) amoebic colitis

• (d) Crohn disease

Q13. Biopsy of inflamed ileum shows non-caseating granulomas in the bowel wall. This favours

• (a) Crohn disease

• (b) ulcerative colitis

• (c) coeliac disease

• (d) tuberculosis always

Q14. Deep longitudinal and transverse ulcers separated by swollen mucosa give the Crohn bowel a

• (a) lead-pipe appearance

• (b) cobblestone appearance

• (c) apple-core appearance

• (d) string-of-pearls appearance

Q15. A patient has bloody diarrhoea; colonoscopy shows continuous mucosal inflammation starting at the rectum. The likely diagnosis is

• (a) ischaemic colitis

• (b) diverticulitis

• (c) ulcerative colitis

• (d) Crohn disease

Q16. Islands of regenerating mucosa projecting above ulcerated areas in ulcerative colitis are called

• (a) adenomas

• (b) pseudopolyps

• (c) granulomas

• (d) hamartomas

Q17. Which feature points to Crohn disease rather than ulcerative colitis?

• (a) fistulas and abscesses

• (b) rectal involvement

• (c) bloody diarrhoea

• (d) pseudopolyps

Q18. A patient with ulcerative colitis has raised alkaline phosphatase and GGT. Suspect

• (a) Gilbert syndrome

• (b) primary sclerosing cholangitis

• (c) gallstones only

• (d) hepatitis A

Q19. A woman with diarrhoea and iron deficiency has villous atrophy on duodenal biopsy. The most useful blood test is

• (a) CEA

• (b) stool culture

• (c) ANA

• (d) tissue transglutaminase IgA (and endomysial IgA)

Q20. In suspected coeliac disease with conflicting biopsy and serology, a negative test for HLA-DQ2 and DQ8

• (a) means lymphoma

• (b) effectively rules coeliac disease out

• (c) is irrelevant

• (d) confirms it

Q21. A man from southern India has chronic diarrhoea with malabsorption and megaloblastic anaemia. Coeliac serology is negative. Likely diagnosis and treatment:

• (a) tropical sprue — tetracycline plus folate for 6 months

• (b) coeliac disease — gluten-free diet

• (c) Whipple disease — no treatment

• (d) giardiasis — metronidazole once

Q22. A middle-aged man has arthritis, weight loss, diarrhoea and abdominal pain; small-bowel biopsy shows the organism. The bacterium is

• (a) Clostridioides difficile

• (b) Tropheryma whipplei

• (c) Giardia

• (d) Mycobacterium avium

Q23. The usual cause of luminal obstruction in acute appendicitis is

• (a) lymphoid hyperplasia

• (b) worms

• (c) foreign body

• (d) carcinoid tumour

Q24. An elderly woman has unexplained iron-deficiency anaemia and occult blood in stool; colonoscopy finds a caecal mass. Right-sided colon cancers typically present with

• (a) jaundice

• (b) bleeding and anaemia

• (c) early obstruction

• (d) pencil-thin stools

Q25. Most colorectal cancers arise from

• (a) normal mucosa directly in all cases

• (b) adenomatous polyps

• (c) juvenile polyps

• (d) hyperplastic polyps

Q26. Which hereditary syndrome predisposes to colorectal cancer?

• (a) Turner syndrome

• (b) Gilbert syndrome

• (c) Marfan syndrome

• (d) Lynch syndrome

Q27. In colon cancer, a raised serum CEA is found in about

• (a) 90% of early cancers

• (b) no patients

• (c) a third of patients — so it is not a screening test

• (d) all patients

Q28. A submucosal gastric tumour shows a mutation in C-KIT. The tumour is a

• (a) gastrointestinal stromal tumour (GIST)

• (b) lymphoma

• (c) adenocarcinoma

• (d) carcinoid

Q29. The commonest site of GIST is the

• (a) appendix

• (b) oesophagus

• (c) stomach

• (d) rectum

Q30. In severe ulcerative colitis, megacolon is defined radiologically as a transverse colon diameter above

• (a) 10 cm

• (b) 15 cm

• (c) 3 cm

• (d) 6 cm

Active Recall

From memory: give the risk factors of oral cancer; compare oesophageal SCC and adenocarcinoma; list peptic ulcer causes and duodenal pain pattern; describe gastric cancer and linitis plastica; contrast Crohn disease and ulcerative colitis; give coeliac serology, tropical sprue treatment and the cause of appendicitis; and describe colorectal cancer by side, its origins and GIST.