Skip lesions are feature of -

Ans. is 'd' i.e., Crohn's disease o A classic feature of CD is the sharp demarcation of diseased bowel segments from adjacent uninvolved bowel.When multiple bowel segments are involved, the intervening bowel is normal - skip lesionsCrohn disease (Terminal ileitis or regional enteritis)o Most commonly small intestine (especially distal ileum) is involvedfin 40% cases). Both small intestine and colon are involved in 30% of cases, and only colon is involved in 30%.In the affected segment, mesenteric fat wraps around the bowel surface - creeping fato The intestinal wall is rubbery and thick, as a consequence of edema, inflammation, fibrosis, and hypertrophy of the muscularis propria - lumen is almost always narrowed - string sign on barium mealo There are serpentine linear ulcer along the axis of bowel.o As the intervening mucosa tends to be relatively spared, the mucosa acquires a coarse texture - Cobblestone appearance.o There is transmural inflammation affecting all layers of bowel wall.o Sarcoid like noncaseating granulomas may be present in all tissue layerso Neutrophilic infiltration into the crypts results in formation of crypt abscesso On barium enema there is Hose pipe (lead pipe) appearance and cobble - stone appearanceo Screening test is presence of anti-Saccharomyces cerevisae antibody (ASCA). Antibody formation is common against cell wall of yeast, Saccharomyces cerevisae in patients of CD.