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Imaging of the luminal gut: Crohn's disease, colitis, bowel and gastric tumours
On CT or MR enterography Crohn's disease is recognised by segmental wall thickening with enhancement, the "comb sign" and creeping fat; colitis is distinguished by location and wall thickness; and in the stomach a benign ulcer projects beyond the wall line while a malignant ulcer stays within it.
Why it matters in the exam
Crohn's disease: segmental involvement (skip lesions), mainly in the terminal ileum; wall above 3 mm with strong enhancement, the "comb sign" (engorged vasa recta), creeping fat, strictures, fistulae and abscesses. MR enterography is preferred in young patients and for follow-up, without radiation; pelvic MRI for perianal fistulae. Ulcerative colitis: continuous from the rectum upward, loss of haustra ("lead pipe") in the chronic stage and "backwash" ileitis. Pseudomembranous colitis (C. difficile): marked wall thickening of the whole colon, the "accordion sign". Ischaemic colitis — the splenic flexure and rectosigmoid junction; typhlitis in a neutropenic patient — the caecum.
Small bowel tumours: NET (carcinoid) — in the terminal ileum, with a calcified mesenteric mass and a "stellate" desmoplastic reaction; adenocarcinoma — duodenum and proximal jejunum, a short stricture and obstruction; lymphoma — long wall thickening with "aneurysmal dilatation" of the lumen without obstruction; GIST — an exophytic enhancing mass. Coeliac disease: loss of jejunal folds and increased ileal folds ("pattern reversal"), transient intussusceptions and mesenteric lymph nodes. FAP: hundreds of colonic polyps, desmoid tumours and periampullary adenomas. Mesenteric panniculitis: dense mesenteric fat with a preserved "fat halo" around the vessels and a pseudocapsule. Peritoneal carcinomatosis: "omental cake" and scalloping of the liver margin.
Stomach and oesophagus: a benign ulcer projects outside the wall line, with a "Hampton line" and folds reaching the ulcer margin; a malignant ulcer lies within the luminal line, with irregular thickened folds that stop short of the margin. Linitis plastica — a rigid stomach that does not distend ("leather bottle"). Gastric lymphoma versus adenocarcinoma: in lymphoma marked thickening with preserved pliability, crossing of the pylorus and large lymph nodes also below the renal hilum. Ménétrier disease — giant folds in the fundus and body sparing the antrum. Oesophageal cancer: EUS for T and N stage, CT and PET-CT for metastases. Hiatal hernia on barium swallow: the gastro-oesophageal junction 2 cm or more above the diaphragm.
Key points
- Crohn's — segmental, terminal ileum, comb sign.
- Ulcerative colitis — continuous from the rectum.
- NET — calcified stellate mesenteric mass.
- Lymphoma — thickening with a wide lumen and no obstruction.
- A benign ulcer projects beyond the wall line.
Summary table
| Condition | Location | Key finding | Distinguishing feature |
|---|---|---|---|
| Crohn's disease | Terminal ileum, segmental | Thick wall, comb sign, creeping fat | Fistulae and strictures |
| Ulcerative colitis | Continuous from the rectum | Loss of haustra | Backwash ileitis |
| Pseudomembranous colitis | Whole colon | Marked thickening, accordion sign | Recent antibiotics |
| Small bowel NET | Terminal ileum and mesentery | Calcified mass with stellate reaction | Carcinoid syndrome with liver metastases |
| Bowel lymphoma | Small bowel or stomach | Long thickening, aneurysmal dilatation | No obstruction |
Free exam questions
מה נכון לגבי Mesenteric Panniculitis – Sclerosing Mesenteritis ? (the question as examined, in Hebrew)
- א. מצב שכיח, לרוב סימפטומטי
- ב. בפניקוליטיס ב - CT נראית מסה בצפיפות שומן, לרוב ב - RLQ
- ג. " פיתולי מעי סמוכים לרוב מעורבים עם HALO" .סביבם
- ד. מדובר בתהליך דלקתי, לרוב עם.פרוגנוזה טובה
בת 27 , ברקע מחלת קרוהן ידועה מזה מספר שנים. בשנים האחרונות ברמיסיה תחת טיפול ב- adalimumab . כעת בשבוע 8 להריון. איזה מהמשפטים הבאים נכון בהקשר לניהול המקרה ? (the question as examined, in Hebrew)
- א. ,יש להמליץ על הפסקת הטיפול התרופתי בשל סיכון גבוה להפלה יש לשקול שימוש בסטרואידים במידת הצורך
- ב. יש לשקול הפסקת הריון בשל טרטוגניות של הטיפול שקיבלה עד עתה
- ג. יש להמליץ על החלפת הטיפול התרופתי ל- vedolizumab בשל פרופיל הבטיחות של התרופה בהריון
- ד. יש להימנע ממתן חיסונים חיים לתינוק/ת עד גיל שנה
בן 40 עם ulcerative colitis מאובחן עם primary sclerosing cholangitis . מה תהיה ההשפעה של הטפול במחלת המעי על primary sclerosing cholangitis ? (the question as examined, in Hebrew)
- א. טיפול ביולוגי יעיל תמנע את המשך התקדמות המחלה בדרכי המרה
- ב. טיפול ביולוגי יעיל תגרום לנסיגה של המחלה בדרכי המרה
- ג. כריתת המעי החולה תמנע את המשך התקדמות המחלה בדרכי מרה
- ד. לטיפול במעי לא תהיה כ ל השפעה על התקדמות המחלה בדרכי המרה
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Sources
- ECCO-ESGAR Guideline for Diagnostic Assessment in IBD, Part 1: Initial diagnosis, monitoring of known IBD, detection of complications, 2019 — Cross-sectional imaging
- ESGAR Consensus Statement on CT and MR Enterography, 2017 — Technique and findings
- ACR Appropriateness Criteria: Crohn Disease, 2019 — Initial imaging
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-06. The text may contain errors; when in doubt, check the source.