Crohn's disease

Etiology and pathogenesis

Although the exact etiology of the disease remains unknown, it is believed to be based on a complex combination of infectious and genetic factors. An autoimmune component plays a significant role, as confirmed by the systemic nature of the lesions and the high efficacy of immunosuppressors. Marked impairments in both cellular and humoral immunity are observed in the patient's body.

The microscopic picture is extremely specific. The inflammation is transmural—lymphocytes and plasma cells infiltrate absolutely all layers of the bowel wall. In 50% of cases, inflammatory infiltrates are found in the form of granulomas containing multinucleated giant cells. The progression of this inflammatory process leads to severe consequences:

• Sclerosis of the bowel wall.
• Formation of strictures (luminal narrowing).
• Formation of abscesses and fistulas.

Laboratory diagnostics

Laboratory methods help assess the systemic inflammatory response and the degree of digestive impairment:

1. Coprological examination: allows detection of maldigestion and malabsorption syndromes. Steatorrhea, amylorrhea, and creatorrhea are found in the stool. A specific sign of the small intestinal or mixed form of the disease is steatorrhea with a predominance of fatty acids and their salts.
2. Hematological analysis: reflects general inflammation (leukocytosis, accelerated ESR) and bodily exhaustion (anemia).

Instrumental methods

Diagnostic imaging (radiological examination) plays a crucial role in visualizing mucosal and submucosal changes. Due to edema and inflammation, folds become flattened or thickened, and the wall becomes rigid. The relief acquires a granular appearance with small filling defects. Pathognomonic symptoms include:

• «Cobblestone» sign: formed by deep longitudinal and transverse ulcers.
• «String» sign: cord-like narrowing of the lumen, most commonly detected in the distal ileum.
• Detection of complications such as strictures and fistulas (especially in the ileocecal region).

Endoscopic methods are essential for direct visualization and biopsy collection:

• Colonoscopy: evaluates lesions of the large intestine and terminal ileum, helps identify strictures and monitor relapses after surgical interventions.
• EGD (Esophagogastroduodenoscopy): used to diagnose upper GI tract (gastric) involvement, which is rare (1–1.5%) and usually indicates terminal-stage disease.

Treatment

Therapy for Crohn's disease is divided into conservative and surgical.

Conservative treatment is the mainstay of patient management and includes a combination of glucocorticoids and sulfasalazine-group drugs, which suppress the inflammatory process.

Surgical intervention does not cure the disease and is therefore strictly indicated for the development of life-threatening complications, such as:

• Intestinal obstruction;
• Abscesses;
• Fistulas.

Briefly: answers to topical questions

Class and exam questions

What else to study on this topic

• Clinical presentation and main symptoms of the disease during an exacerbation phase
• Mechanisms of malabsorption syndrome development
• Extraintestinal manifestations of the autoimmune component
• Differential diagnosis with ulcerative colitis (UC)

Other topics in the "Digestive System" section

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