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?

Answer: a) Crohn's colitis (BAILEY 26TH ED, P-1151)INFLAMMATORY BOWEL DISEASEPeak age of presentation 15-30 years and 60-80 yearsFemales > malesCROHN'S 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-DR1/DQw5HLA-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 (35%)No granulomasModerate pseudopolypsMarked number of Pseudopolyps (tips fuse to form mucosal bridges)Deep, 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 (MC)Right lower quadrant mass, weight loss, anemiaSometimes mimics appendicitis or bowel perforationRelapsing disorder with attacks of bloodydiarrhea (usually nocturnal/postprandial),cramps, fecal urgencyAnal complaints (fissure, fistula, abscess) - frequentInfrequentLess incidence of perforationIncreased incidence of perforationFat/vitamin malabsorption presentAbsentMalignant potential + with colon involvementMalignant potential (UC > CD)Recurrence after surgery commonRareToxic megacolon - not commonToxic megacolon seen (diameter > 6 cm)Investigations70% ASCA +ve (anti Saccharomyces cerevisiae Ab)10% 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 (CD=UC) - 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 (UC>CD) - 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 > UC)Pyoderma vegetans, pyostomatitis vegetans, Sweet syndrome (neutrophilic dermatosis)