Pathology
Gastrointestinal Tract
Gastrointestinal pathology for MBBS and NEET-PG: oral cancers, peptic ulcer and H pylori, gastric carcinoma, intestinal tuberculosis and inflammatory bowel disease, mapped to NMC codes PA24.1 to PA24.7.
MedNext Academy | 3 min read
Gastrointestinal Tract
Gastrointestinal pathology for MBBS and NEET-PG: oral cancers, peptic ulcer and H pylori, gastric carcinoma, intestinal tuberculosis and inflammatory bowel disease, mapped to NMC codes PA24.1 to PA24.7.
This chapter covers the pathology of the gastrointestinal tract. It includes oral cancers, peptic ulcer disease and its link with Helicobacter pylori, gastric carcinoma, intestinal tuberculosis and the inflammatory bowel diseases, with an emphasis on the features that distinguish them.
High-yield: Gastrointestinal Tract
- Oral squamous cell carcinoma is strongly associated with tobacco and areca nut chewing, common in India.
- Oral submucous fibrosis is a premalignant condition linked to areca nut, causing trismus and mucosal stiffness.
- Peptic ulcer disease is caused mainly by Helicobacter pylori infection and by non-steroidal anti-inflammatory drugs.
- Duodenal ulcers are usually benign, while gastric ulcers must be biopsied to exclude malignancy.
- Helicobacter pylori is a curved gram-negative bacillus that colonises gastric mucus and causes chronic gastritis.
- Gastric adenocarcinoma is of intestinal type (often on a background of intestinal metaplasia) or diffuse type.
- The diffuse type of gastric cancer shows signet-ring cells and can cause linitis plastica, a rigid leather-bottle stomach.
- A Virchow node (left supraclavicular) and a Krukenberg tumour (ovarian metastasis) are classic spread patterns of gastric cancer.
- Intestinal tuberculosis most often affects the ileocaecal region and shows transverse ulcers and caseating granulomas.
- Crohn disease is transmural, has skip lesions, non-caseating granulomas and a cobblestone mucosa.
- Ulcerative colitis is a continuous mucosal disease starting in the rectum, with crypt abscesses and pseudopolyps.
- Crohn disease can affect any part of the gut from mouth to anus, whereas ulcerative colitis is confined to the colon.
- Colorectal carcinoma commonly arises from adenomatous polyps through the adenoma-carcinoma sequence.
- Apple-core narrowing on a barium study and iron deficiency anaemia are classic pointers to a left-sided colonic carcinoma.
Crohn disease versus ulcerative colitis
- **Distribution:** Crohn: mouth to anus, skip lesions. UC: colon only, continuous from rectum.
- **Depth:** Crohn: transmural. UC: mucosa and submucosa.
- **Histology:** Crohn: non-caseating granulomas. UC: crypt abscesses, no granulomas.
- **Gross:** Crohn: cobblestone mucosa, fistulae. UC: pseudopolyps, toxic megacolon.
NMC competencies in this chapter
- **PA24.1:** Aetiology, pathogenesis, pathology and clinical features of oral cancers
- **PA24.2:** Aetiology, pathogenesis, microbiology and features of peptic ulcer disease
- **PA24.3:** Identify the microscopic features of peptic ulcer
- **PA24.4:** Aetiology, pathogenesis and pathology of carcinoma of the stomach
- **PA24.5:** Aetiology, pathogenesis and pathology of tuberculosis of the intestine
- **PA24.6:** Aetiology, pathogenesis and distinguishing features of inflammatory bowel disease
- **PA24.7:** Integrated approach to gastrointestinal pathology specimens
Frequently Asked Questions
What organism causes most peptic ulcers?
Helicobacter pylori, a curved gram-negative bacillus that colonises the gastric mucosa, along with non-steroidal anti-inflammatory drugs.
How do Crohn disease and ulcerative colitis differ?
Crohn disease is transmural with skip lesions and granulomas anywhere from mouth to anus, while ulcerative colitis is a continuous mucosal disease confined to the colon.
What is linitis plastica?
A rigid, thickened leather-bottle stomach caused by diffuse-type gastric carcinoma infiltrating the wall with signet-ring cells.
Where does intestinal tuberculosis usually occur?
In the ileocaecal region, where it produces transverse ulcers and caseating granulomas.
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