This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Medicine
Comb sign in CT abdomen is seen in: 
Select and explain. 
A. Crohns disease, B. Ulcerative colitis, C. Tuberculosis, D. Intestinal lymphoma
A: Crohns disease
Answer: A: Crohns disease 
Explanation: CT finding in Crohns disease: Mural thickening with stratification is seen with active inflammation Vascular engorgement of the mesentery (comb sign) Hypodense lymph nodes CT findings in intestinal tuberculosis: Mural thickening with contiguous ileo-cecal involvement Hypodense lymph nodes with peripheral enhancement Ref: World J Gastroenterol. 2011 January 28; 17(4): 433-443.