Which of the following is the earliest change in intestine which occurs in Crohn's disease?

Ans. b. Aphthous ulcerRef: Robbins and Cotran Pathologic Basis of Disease 9th Ed; Page No- 797 Crohn's diseaseUlcerative colitisLocationTerminal ileum and colonSegmental with skip lesions, rectal sparingRectum; sigmoid colon, continuous colonic lesionsGross Morphology*. Transmural inflammation noncaseating granuloma formation with lymphoid aggregates in mucosa*. Cobblestone mucosa, creeping fat, bowel wall thickening ("string sign" on barium swallow X-ray), linear ulcers, fissures*. Fibrosis commonly seen*. Mucosal and submucosal inflammation only*. Friable mucosa with superficial and/or deep ulcerations (compare normal with diseased)*. Fibrosis is rareMicroscopic Morphology*. It is chronic noncaseating granulomas*. Associated with HLA-DR-1*. Thl mediated.*. TH17 cells may also be contributory.*. IL-23 receptor polymorphisms is protective*. Crypt abscesses and ulcers, bleeding, no granulomas.*. Associated with HLA-DR-2*. Th2 mediated*. IL-10 gene polymorphism is associated with UC. s Crohn's diseaseUlcerative colitisComplications*. Malabsorption/malnutrition, colorectal cancer (increases risk with pancolitis)*. Fistulas (e.g. enterovesical fistulae, which can cause recurrent UTI and pneumaturia), phlegmon/ abscess, strictures (causing obstruction), perianal disease*. Hosepipe appearance*. Fulminant colitis,*. Toxic megacolon present*. Perforation is rare*. Loss of haustra - "lead pipe" appearance on imaging*. Garden-hose appearanceIntestinal Manifestation* Diarrhea that may or may not be bloody* Bloody diarrheaExtra intestinal Manifestations*. Rash (pyoderma gangrenosum, erythema nodosum), eye inflammation (episcleritis, uveitis), oral ulcerations (aphthous stomatitis), arthritis (peripheral, spondylitis)*. Kidney stones (usually calcium oxalate), gallstones*. May be [?] for anti-Saccharomyces cerevisiae antibodies (ASCA)*. 1deg sclerosing cholangitis.*. Associated with p-ANCATreatmentCorticosteroids, azathioprine, antibiotics (e.g. ciprofloxacin, metronidazole), infliximab, adalimumab5-aminosalicylic preparations(e.g. mesalamine), 6-mercaptopurine, infliximab,colectomy Crohn's diseaseUlcerative colitis