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Colon

Infectious colitis

Tuberculosis

Author: Elliot Weisenberg, M.D.

Editorial Board Member: Raul S. Gonzalez, M.D.

Last author update: 1 November 2016

Last staff update: 10 May 2022

Copyright: 2003-2023, PathologyOutlines.com, Inc.

PubMed Search: Tuberculosis[title] colon

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Table of Contents

Cite this page: Weisenberg E. Tuberculosis. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/colonTB.html. Accessed April 1st, 2023.

Definition / general

Infection of the colon or small intestine by Mycobacterium tuberculosis
See Mycobacteria infections other than TB for discussion of the less common M. bovis, M. africanum, M. canetti, M. microti

Essential features

Infection occurs by swallowing mycobacteria in sputum (or less commonly infected milk), miliary spread or direct extension from an involved lymph node or the fallopian tube
Ileocolonic disease often occurs in the absence of active pulmonary disease
Common symptomatology includes weight loss, anorexia, fever, abdominal pain, diarrhea and palpable mass
Endoscopic findings include strictures, ulcers and mucosal hypertrophy
Biopsies show granulomatous inflammation with confluent granulomas, usually with caseous necrosis
Mycobacteria are detected by special stain, culture, nucleic acid amplification or PCR
Treatment is with multiple antibiotics and more aggressive treatment is necessary for multidrug resistant and extensively drug resistant TB
Surgery may be necessary in the setting of perforation or obstruction
Today, colonic TB is uncommon but in the preantibiotic era, 70% of patients who died developed gastrointestinal TB

ICD coding

ICD-10: A18.32 - tuberculous enteritis

Epidemiology

Worldwide (2015): 10.4 million cases of TB and 1.8 million deaths (WHO: Tuberculosis [Accessed 18 October 2021])
United States (2015): 9557 cases, rate 3.0 per 100,000 (CDC: Reported Tuberculosis in the United States, 2015 [Accessed 18 October 2021])
Approximately 1/3 of world's population has evidence of TB infection
Disease of poverty; 95% of cases occur in developing world (61% Asia, 26% Africa)
Usually affects young to middle aged adults but all at risk
Under 5% of cases of active TB represent intestinal TB
Extrapulmonary TB more common in AIDS patients
Risk factors: HIV / AIDS, substance abuse, silicosis, diabetes mellitus, chronic kidney disease, malnutrition, organ transplant, head and neck cancer, old age, infancy, immunosuppressive therapy, use of biologic treatments such as infliximab for immune mediated disease

Sites

Most common in cecum in conjunction with ileum (abundant lymphoid tissue); 70% of patients with gastrointestinal TB have ileocecal disease
Also other colorectal sites
Multiple sites in 28 - 44%
Ileocecum is most common site of abdominal and gastrointestinal TB
Isolated colorectal involvement is uncommon - only 10.8% of abdominal gastrointestinal TB

Pathophysiology

Non spore forming, aerobic, nonmotile bacillus with high lipid and mycolic acid content of cell wall
Slow growth, generation time 15 - 20 hours
Phagocytosed by macrophages, blocks formation of phagolysosome, replication occurs; bacteremia develops (primary TB)
Th1 response develops that allows macrophages to contain bacteria
Granulomatous inflammation with necrosis and tissue damage occurs
Contained infection usually becomes hyalinized and calcified
Reactivation may occur with diminished immune status
Usually infection is contained, 5 - 10% develop active disease but 30% with HIV
Spread to GI tract via swallowed bacteria, hematogenous spread, direct extension from infected lymph nodes or fallopian tube
Ileocecum a favored site in GI tract due to abundance of lymphoid tissue

Clinical features

Colon

Usually chronic disease is present for months
Generally weight loss, fever, abdominal pain, diarrhea and often a palpable abdominal mass
May see night sweats, anorexia, GI bleeding, malabsorption
Perforation or intestinal obstruction may occur

Small intestine

Disease occasionally seen in less developed countries
Small intestinal disease may be transmitted via contaminated milk
Symptoms: abdominal pain, malabsorption, strictures, perforation, fistula

Diagnosis

Diagnosis may be established by biopsy with demonstration of microorganisms with special stain, culture or molecular techniques

Laboratory

Nucleic acid amplification tests and PCR based assays, Xpert MTB / RIF test detects TB and rifampicin resistance, auramine-rhodamine or Ziehl-Neelsen smear of fresh tissue, Ziehl-Neelsen or Kinyoun stain of paraffin embedded tissue, culture (long turnaround time but recommended for confirmation)
Detection of antibiotic resistance is important (multidrug resistant or extensively drug resistant TB)

Radiology description

Early nodular mucosal thickening with loss of symmetry in the fold pattern
May see fissures, sinus tracts, fistulae (rare), ulceration (perpendicular to long axis, cf. Crohn's disease), perforation
Obliteration of ileocecal angle with widely patent ileocecal valve
Rapid emptying of inflamed terminal ileum (Stierlin sign)
Often associated mesenteric lymphadenopathy with increased mesenteric thickness

Prognostic factors

Worse prognosis in HIV with low CD4 counts, other immunodepressed states, elderly, debilitated

Case reports

35 year old woman with synchronous ileocecal and duodenal tuberculosis (Int J Colorectal Dis 2014;29:1027)
35 year old woman with tubercular duodenal, jejunal and ileocecal stricture (BMJ Case Rep 2013;2013:bcr2013200347)
41 year old man with cecal tuberculosis mimicking submucosal tumor (Intern Med 2016;55:1859)
45 year old man with rectal tuberculosis presenting with rectal prolapse and masquerading as malignancy (Indian J Tuberc 2013;60:184)

Treatment

Inflammatory cecal masses can mimic acute appendicitis, leading to surgery (World J Emerg Surg 2014;9:7)
Generally isoniazid (INH), rifampin, ethambutol (EMB) and pyrazinamide (PZA) for 6 to 9 months (with HIV, use an intensive phase of INH, a rifamycin, PZA and EMB for the first 2 months with continuous INH and a rifamycin for the last 4 months)
Drug resistant TB is resistant to at least one first line drug, extensively drug resistant is resistant to INH and rifampin, plus at least one of three injectable second line drugs (amikacin, kanamycin or capreomycin)
The CDC recommends expert consultation to treat drug resistant and extensively drug resistant TB

Gross description

Ulcerative (most common), hypertrophic and mixed forms are described
Usually multiple superficial ulcers perpendicular to long axis of bowel; may see deep ulcers
May see thickened mucosal folds, strictures, ulcers, inflammatory nodules; fistulas are rare

Microscopic (histologic) description

Caseating granulomas, often confluent and numerous, often cuff of lymphocytes, lymphoid hyperplasia, aphthous to deep ulcers, often architectural distortion
AFB stains more likely to be positive in necrotic areas and histiocytes, bacteria may be rare to abundant
Hyalinization and calcification with chronicity / treatment
Destruction of muscularis propria, scarring

Microscopic (histologic) images

Contributed by Raul S. Gonzalez, M.D. and Elliot Weisenberg, M.D.