This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Skin, Subject name: Medicine
Skip granulomatous lesions are seen in- 
Select and explain. 
A. Ulcerative colitis, B. Crohn's disease, C. Whipple's disease, D. Reiter's disease
B: Crohn's disease
Answer: B: Crohn's disease 
Explanation: Ans. is 4b' i.e., Crohn's diseaseSkip lesions are characteristic of Crohn's disease.o This pt. is suffering with Crohn's ds.o The characterstics of Crohn's ds and their comparison with Ulcerative colitis are given -Once you know them the answer becomes obvious.FeaturesUlcerative colitisCrohn's dso Rectal involvemento Distribution of lesionso Mucosal appearanceo Associated ileal>90%ContinuousFriable, diffusely involved 10%, mild, terminal ileal InflammationRectum spared in > 50%Skip lesionsCobblestone appearance 50% have combined ileal and colonic involvement.o Perianal abcess, fistulaso Intestinal strictures & obstructiono Intestinal fistulaso Fissures (Radiological)o Toxic megacolono Extraintestinal Manifestation -RareNot seen Not seen Not seenRare but more than crohns dsCommonCommonCommonCommonVery rarey Sclerosing pericholangitisy Uveitis & Arthritisy Pyoderma gangrenosumCommonCommonCommonRareCommonRarePathological Features o Depth of inflammationo Creeping mesentric fato Fibrous thickening of wallo Pseudopolypso Granulomaso Dysplasiao CarcinomaMucosalNot seenCommon (lead pipe)CommonNot seenCommon10%TransmuralCommonRareRareCommonRareRare