13 intestinal tuberculosis

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INTESTINAL TUBERCULOSIS


INTESTINAL TUBERCULOSIS •

Types:

• • •

Primary intestinal tuberculosis Secondary intestinal tuberculosis Hyperplastic intestinal tuberculosis

PRIMARY INTESTINAL TUBERCULOSIS:

• • • •

Occurs in previously unexposed individuals Due to ingestion of contaminated cow’s milk by Mycobacterium Bovis Occurrence – rare, because control of TB in cattle and pasteurization of milk So, now cases are caused by Mycobacterium TB due to ingestion of contaminated cow’s milk and swallowing of coughed – up organisms

Morphology:

• •

Gross: Matted, enlarged, caseous, fibrosis, and calcification Microscopic: Initially Ghon focus in intestine, later mesenteric

Mesenteric lymph nodes involvement and initially without any significant lesion in small intestine

(typical TB granulomas with caseous necrosis seen)

lymph nodes are affected


Tuberculosis small intestine Gross – both external and cut opened •

The small intestine is identified externally by absence of taenia coli band, appendices epiploicae and haustrations

Mesentry shows an enlarged lymph node in cut section having areas of caseation necrosis

(1). The lumen shows transverse ulcers and strictures (transverse to the long axis of intestine)


Tuberculosis small intestine Gross - cut opened •

(2). The intestinal wall in the strictrous areas is thickened and gray white and mucosa ulcerated

•

The mucosal surface in the intervening areas shows irregularity of mucosal folds


SECONDARY INTESTINAL TUBERCULOSIS:

Occurs due to self swallowing of sputum loaded with T.Bacilli by patients with active TB

Lesion: terminal ileum… Payer’s patches or lymphoid follicles

• • •

Microscopic : Presence of Tubercles Mucosa and submucosa: ulceration Muscularis layer: Fibrosis

TB peritonitis may occur

HYPERPLASTIC INTESTINAL TUBERCULOSIS:

• • • •

Variant of secondary TB Common site: Caecum and ascending colon Gross: Thick walled and mucosal ulceration seen Important Differential Diagnosis: Carcinoma

Microscopic: Presence of caseating Tubercles

Important Differential Diagnosis: Crohn’s disease, Non caseating granuloma of sarcoidosis

small ulcers coalesce to form large ulcers (transverse to the long axis of bowel versus Typhoid ulcer)


Intestinal Amoebiasis • • • •

Due to ingestion of cyst form of entamoeba histolytica leads to infection Cyst wall dissolved in small intestine Amoeba liberation Settles in large intestine (commonly affected site)

• Pathology: Amoeba e cause epithelial damage (by means of gland invasion and formation • •

of flask - shaped ulcers ( narrow neck and broad base) Amoebae can also cause liver abscess Systemic infection – rare

• Gross: Small areas of elevation in the mucosa •

Later flask shaped ulcers

• Site: Caecum, rectum and colonic flexures • Microscopic: Ulcer with chronic inflammatory cell infiltrate (lymphocytes, plasma cells, •

macrophages and eosinophils Trophozoites seen in the edge of ulcers with inflammatory exudates

• Complications: Amoebic liver abscess, perforation, hemorrhage and formation of tumor like mass in the large intestine (amoeboma)


Amoebic ulcers large intestine Gross – both external and cut opened

The large intestine is identified externally by the presence of taenia coli bands, appendices epiploicae and haustrations

(1). The luminal surface shows multiple ulcers some of which are deep and are flask-shaped with narrow neck and broad base


Amoebic ulcers large intestine Gross - cut opened •

(2) containing necrotic tissue and undermined margins


Entamoeba histolytica in colon High-power view of the organisms Note some of the organisms ingesting red blood cells


Other miscellaneous ulcerative lesions of large intestine •

Infectious enterocolitis:

1. Viral gastroenterocolitis – rotavirus, caliciviruses and adenovirus 2. Bacterial enterocolitis - salmonella, shigella, V.cholerae and E.Coli 3. Parasitic enterocolitis – nematodes (round worms), cestodes (hook worms)and protozoa 4. Necrotizing enterocolitis – occurs in low birth weight or premature neonates 5. Collagenous and lymphocytic colitis – common in middle aged females - endoscopic findings are grossly normal - So it is called “ microscopic colitis” 6. Antibiotic associated colitis – after massive broad spectrum antibiotic therapy normal GI tract flora destroyed , so colitis developed 7. Associated with autoimmune disease – seen in systemic sclerosis - GI tract ulcer and fibrosis


Infectious enterocolitis

• Miscellaneous A. AIDS – associated diarrheal illness B. Transplantation associated C. Drug induced D. Radiation enterocolitis E. Neutropenic colitis F. Diversion colitis G. BIRRU (Benign Idiopathic Recurrent Rectal Ulcer)

Contd..


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