Colon
Continuous inflammation from the rectum with bloody diarrhoea is ulcerative colitis, which is limited to the mucosa and colon.
What our notes say
- Continuous inflammation from the rectum with bloody diarrhoea is ulcerative colitis, which is limited to the mucosa and colon. (Endocrinology and Gastroenterology Question Bank: 12 Clinical MCQs)
- A colonoscopy reveals mucosal edema and ulceration in the ascending colon, but the transverse and descending portions of the colon are not affected. (Gastrointestinal and liver — Past Paper Questions & Answers)
- Haustral contractions: in the colon, circular muscle contracts at intervals and forms sac-like haustra that mix the contents and aid water absorption. (General Surgery CAT 2 (MBSG 4600): 4 October 2021)
- Mass movements: powerful peristaltic contractions in the colon, 1 to 3 times a day, that push faecal matter into the rectum and trigger defecation (gastrocolic reflex). (General Surgery CAT 2 (MBSG 4600): 4 October 2021)
- Acute pancreatitis typically gives a sentinel loop or colon cut-off sign. (Internal Medicine CAT 1 (MBChB 4), 2022: liver, pancreas and bone marrow, 30 MCQ)
- Colonoscopy shows diffuse erythema and ulcerations in the entire colon and patchy ulceration in the terminal ileum. (Internal Medicine 4th Year 1st Semester CAT: HIV and the gut, liver disease and )
Study material on Colon
- GASTROINTESTINAL PATHOLOGY (Part 2)
- Gastrointestinal and liver
- Gastropathology Pathology
- Hallmarks of Cancer: Molecular Basis, Cell Cycle & Oncogenes
- ONCOPATHOLOGY - 30 KEY SHORT ANSWER QUESTIONS Hallmarks 1,2 & 3
- Medical MCQs: Chemical Pathology & Haematology Exam Review
- Master First-Year Anatomy: Must-Know Essays & Key Concepts
- Pinworm (Enterobius vermicularis)
- GIT Physiology Exam Questions
- Amebae
- MCQ: GASTROINTESTINAL PATHOLOGY — 60 MCQs (Redistributed Answers)
- Weekly Year 2: GIT Physiology Exam - April 21, 2026 (Section A: MCQs)
- ONCOPATHOLOGY MCQ EXAMINATION HAllmarks of Cancer 1,2 &3
- Oncopathology Hallmarks of Cancer MCQs
- Entamoeba histolytica and Amoebiasis
- Gastropathology Pathology
Images
Practice questions on Colon
What explains fibre's protective effect against colon cancer?
- Increased transit time leading to greater carcinogen exposure.
- Production of volatile fatty acids (VFAs) like butyrate by bacterial fermentation.
- Decreased water content in the stool.
- Inhibition of essential nutrient absorption.
Answer: B. The bacterial fermentation of fibre produces short-chain fatty acids (SCFAs), particularly butyrate, which serves as an energy source for colonocytes and has anti-cancer properties. Fibre typically reduces transit time, not increases it, and increases stool water content. It does not inhibit essential nutrient absorption.
A 65-year-old man presents with a firm mass in the sigmoid colon. Colonoscopy shows an ulcerated lesion with irregular borders. Biopsy demonstrates invasion through the muscularis propria. Which histological feature most strongly distinguishes this lesion as malignant rather than benign?
- Nuclear pleomorphism
- Presence of goblet cells
- Mucin production
- Glandular architecture
Answer: A. Nuclear pleomorphism (variation in nuclear size and shape) and hyperchromasia are hallmark features of malignancy and are crucial in distinguishing malignant from benign lesions, even when other architectural features are present.
A 65-year-old man presents with a firm mass in the sigmoid colon. Colonoscopy shows an ulcerated lesion with irregular borders. Biopsy demonstrates invasion through the muscularis propria. Which histological feature most strongly distinguishes this lesion as malignant rather than benign?
- Nuclear pleomorphism and hyperchromasia
- Increased mitotic activity
- Presence of necrosis
- Formation of glandular structures
Answer: A. While increased mitotic activity, necrosis, and glandular formation can be seen in both benign and malignant lesions, significant nuclear pleomorphism and hyperchromasia are hallmarks of malignancy and are key features for distinguishing a carcinoma from a benign polyp or adenoma.
What explains fibre's protective effect against colon cancer?
- Fibre directly kills colon cancer cells.
- Fibre leads to rapid transit of carcinogens through the colon.
- Fibre promotes the growth of only cancer-promoting bacteria.
- Fibre increases the production of bile acids.
Answer: B. Dietary fibre, particularly insoluble fibre, can increase stool bulk and accelerate the transit of intestinal contents, including potential carcinogens, through the colon, thus reducing the duration of contact. Fibre does not directly kill cancer cells or promote only cancer-promoting bacteria. While fibre affects bile acid metabolism, its protective effect against colon cancer is more directly linked to transit time
A 65-year-old man is a firm mass in the sigmoid colon. Colonoscopy shows an ulcerated lesion with irregular borders. Biopsy demonstrates invasion through the muscularis propria. Which histological feature most strongly distinguishes this lesion as malignant rather than benign?
- Nuclear atypia
- Increased mitotic activity
- Glandular formation
- Stromal desmoplasia
Answer: A. Nuclear atypia (variation in nuclear size, shape, and chromatin) is a hallmark of malignancy and is crucial for distinguishing benign from malignant lesions, even when other features like invasion are present. While increased mitoses and glandular formation can be seen in both, atypia is a more definitive indicator of malignancy.
A 65-year-old man presents with a firm mass in the sigmoid colon. Colonoscopy shows an ulcerated lesion with irregular borders. Biopsy demonstrates invasion through the muscularis propria. Which histological feature most strongly distinguishes this lesion as malignant rather than benign?
- Presence of goblet cells
- Epithelial dysplasia
- Invasion beyond the submucosa
- Mucinous secretion
Answer: C. Invasion beyond the submucosa (in this case, through the muscularis propria) is the definitive hallmark of malignancy. While epithelial dysplasia is a precancerous change, and goblet cells and mucinous secretion can be present in benign or malignant lesions, invasion is the key differentiator for malignancy.