<prompt> A 25-year-old man has recurrent, indolent fistula in ano. He also complains of weight loss, recurrent attacks of diarrhea with blood mixed in the stool, and tenesmus. Proctoscopy revealed a healthy, normal-appearing rectum. What is the most likely diagnosis?Crohns colitisUlcerative colitisAmoebic colitisIschemic colitis  <response>: Answer: a Crohns colitis BAILEY 26TH ED, P-1151INFLAMMATORY BOWEL DISEASEPeak age of presentation 15-30 years and 60-80 yearsFemales malesCROHNS DISEASE REGIONAL ENTERITIS GRANULOMATOUS COLITIS TERMINAL ILEITISULCERATIVE COLITISCan affect any part of GIT, but me sites - terminal ileum, ileocecal valve, and cecumLimited to colon and rectumHLA-DR1DQw5HLA-DR2, HLA DR103 Smoking is a strong risk factor OCPs and Appendicectomy increase risk Non-smokers, ex-smokers - higher risk Appendicectomy before 20 years protects against UCMorphologySkip lesionsContinuous lesionsThick bowel wallThin bowel wallStrictures commonRareTransmural inflammationLimited to mucosaNon caseating granulomas 35No granulomasModerate pseudopolypsMarked number of Pseudopolyps tips fuse to form mucosal bridgesDeep, knife-like ulcersSuperficial broad-based ulcersFibrosis, serositis - markedMild to nonePerianal disease - painful skin tags, anal fissures, perianalabscesses, fistulasAbsentRectum mostly sparedRectum always involved Earliest lesions - aphthoid ulcers Crypt abscesses Mesenteric fat wraps bowel surface creeping fat Paneth cell metaplasia in the left colon Distortion of mucosal architecture Cutaneous granulomas - metastatic Crohn disease Rectum always involved and disease extends proximally pancolitis and backwash ileitis Crypt abscessClinical featuresIntermittent mild diarrhea, fever, abdominal pain MCRight lower quadrant mass, weight loss, anemiaSometimes mimics appendicitis or bowel perforationRelapsing disorder with attacks of bloodydiarrhea usually nocturnalpostprandial,cramps, fecal urgencyAnal complaints fissure, fistula, abscess - frequentInfrequentLess incidence of perforationIncreased incidence of perforationFatvitamin malabsorption presentAbsentMalignant potential with colon involvementMalignant potential UC CDRecurrence after surgery commonRareToxic megacolon - not commonToxic megacolon seen diameter 6 cmInvestigations70 ASCA ve anti Saccharomyces cerevisiae Ab10 pANCA positive75 pANCA positive10 ASCA veBarium meal follow through or small bowel enema Straightening of valvulae conniventes Multiple defects cobblestone appearance. Cicatrisation narrowing of ileum string sign of Kantor Rose thorn appearance of the bowel wall. Antibodies to E. coli outer membrane porin protein C OmpC, Antibody to I2, Antiflagellin anti-CBir1 CT enterography - first-line test for the evaluation of suspected CD and its complicationsBarium enema Loss of haustrations Narrow contracted colon hose pipe colon Mucosal changes caused by granularity Chronic - narrow contracted colon Fecal lactoferrin - marker for intestinal inflammation Fecal calprotectin - correlate with, predict relapses, detect pouchitisTreatment 5-ASA agents mesalamine not used now Mild to moderate disease involving terminial ileum or ascending colon- Budesonide Severe disease involving proximal small intestine or distal colon - Prednisone Immunomodulators Azathioprine, mercaptopurine, methotrexate and for maintenance of remission or induction of remission along with steroids in severe disease Anti-TNF therapy Infliximab, adalimumab, certolizumab - first-line agents to induce remission in moderate to severe disease and to maintain remission Anti-integrins: Natalizumab anti-a4 integrin - if no response to anti-TNF agents Mild to moderate distal colitis - topical mesalamine is the drug of choice Mild to moderate disease extending above the sigmoid colon- Oral 5-ASA agents- No response - add prednisone- No response- immunomodulators Severe colitis- IV Methylprednisolone- No response - Infliximab- No response - Cyclosporine- No response - Surgery Fulminant colitis Toxic megacolon not improving in 48-72 hours - surgery - Total proctocolectomyExtraintestinal manifestationsRheumatologicInflammatory arthropathy is the most common extraintestinal manifestationPeripheral arthritis CD UC - asymmetric, polyarticular, migratory, mostly affects large joints of the upper and lower extremities, worsens with exacerbations of bowel activityAnkylosing spondylitis CD UC - not related to bowel activity, does not remit with glucocorticoids or colectomy, most often affects the spine and pelvisSacroileitis CDUC - does not correlate with bowel activity DermatologicErythema nodosum CD UC - attacks correlate with bowel activity; skin lesions develop after the onset of bowel symptomsPyoderma gangrenosum UCCD - may occur before the onset of bowel symptoms, course independent of the bowel disease, respond poorly toAphthous stomatitis and cobblestone lesions of the buccal mucosa CD UCPyoderma vegetans, pyostomatitis vegetans, Sweet syndrome neutrophilic dermatosis 