This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: G.I.T., Subject name: Radiology
Thumb print sign in plain x-ray is seen in: 
Select and explain. 
A. Ischeamic colitis, B. Ulcerative colitis, C. Pseudomembranous colitis, D. Appendicitis
A: Ischeamic colitis
Answer: A: Ischeamic colitis 
Explanation: Ans: a (Ischeamic colitis)Ref: Harrison, 17 ed. pg. 1091, 213; Grainger and Allison 5 ed. pg. 889.Thumb printing sign, i.e., bowel wall oedema seen as an early sign in ischaemic colitis. Also seen in: amoebic colitis and ulcerative colitisIschaemic colitis: Most common sites - Watershed areas of colon Splenic flexure (Griffith's point )Descending/sigmoid colon (Sudeck's point)Radiological signs in ischemic colitis:Early: Late :Thumb printing sign Pneumoperitoneum (due to (bowel wall oedema) -perforation) HallmarkPneumatosisintestinalis (air in Luminal narrowing bowel wall) Funneling of bowelOther specific radiological signs related to GIT:String sign : congenital hypertrophic pyloric stenosis String of kantor : Crohn's disease Sawtooth appear- ance : DiverticulosisWhirlpool sign : Midgut volvulus Coffee bean sign : Sigmoid volvulus Claw sign/target sign/meniscus sign:IntussusceptionBridgeThumb print sign in neck x-ray is seen in acute epiglotitis