Скачать или смотреть HOW CROHN'S DISEASE WORKS

On USMLE exams, Crohn’s disease is characterized by transmural inflammation that can affect any part of the GI tract—from mouth to anus—with a predilection for the terminal ileum. Key features include skip lesions, cobblestoning, and creeping fat. Patients often present with non-bloody diarrhea, weight loss, and right lower quadrant (RLQ) pain. Extraintestinal manifestations are common and include fistulas, strictures, perianal disease (often early signs), calcium oxalate kidney stones due to fat malabsorption, erythema nodosum, oral ulcers, and enteropathic arthritis (a seronegative spondyloarthropathy associated with HLA-B27). Histologically, noncaseating granulomas are classic but only found in about one-third of cases. ASCA is often elevated (vs. p-ANCA in ulcerative colitis), though neither is diagnostic. Acute flares are treated with corticosteroids; immunomodulators like azathioprine, 6-MP, or methotrexate are used for maintenance. Anti-TNF agents (e.g., infliximab) are indicated for moderate to severe or refractory disease, but TB must be ruled out first. Complications include vitamin B12 deficiency (if the ileum is involved), strictures, obstruction, malabsorption, and increased colorectal cancer risk (less than UC but still present). Classic imaging finding: the “string sign” on barium studies. Be ready to contrast Crohn disease with ulcerative colitis—it’s a favorite USMLE topic.
#USMLE #USMLEStep1 #USMLEStep2 #Step1Prep #Step2CK #NBME #HIV #CD4Count #Histoplasma #Coccidioides #PJP #Pneumocystis #FungalInfection #MedStudentLife #MedicalSchool #MedEd #InfectiousDisease #Pharmacology #Step1Facts #Step2Tips #Anki #Microbiology #OpportunisticInfection #StudySmart