Tuberculosis

Published on 19/07/2015 by admin

Filed under Radiology

Last modified 22/04/2025

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 Abdominal lymphadenopathy is most common

• Lymphadenopathy (tuberculous lymphadenitis)

image Enlarged, centrally necrotic nodes with hypoattenuating centers and hyperattenuating enhancing rims
image Nodes often calcify after healing
• Tuberculosis peritonitis

image Variables amounts of free or loculated complex ascites with infiltration of omentum ± discrete masses
• Gastrointestinal tuberculosis

image Ileocecal region affected in 90% of cases
image Asymmetric wall thickening of ileocecal valve and medial cecum
• Adrenal tuberculosis

image Acute: Enlarged adrenals (often appears as discrete, centrally necrotic adrenal mass)
image Chronic: Small adrenals with dots of calcification and low signal on all MR sequences
• Renal tuberculosis

image Most common CT finding is renal calcification (50%)
image Papillary necrosis is a very common early finding
image Focal wedge-shaped hypodense areas, small hypodense nodules, or discrete renal abscess
image Urothelial thickening, caseous debris, and strictures of calyces and infundibuli may lead to hydronephrosis
• Hepatosplenic tuberculosis

image Hepatosplenomegaly with hypodense nodules of variable size

CLINICAL ISSUES

• Often presents with fever, weight loss, and abdominal pain
• May or may not have evidence of pulmonary TB

image Negative chest radiograph or negative tuberculin skin test does not exclude extrapulmonary TB
image
(Left) Axial CECT in an asymptomatic elderly man shows calcification of mesenteric nodes image usually seen in elderly individuals who have had exposure to enteric mycobacteria, often from drinking unpasteurized milk.

image
(Right) Axial CECT in a liver transplant recipient shows marked thickening of the omentum image, peritoneum, and mesentery, with enlargement of mesenteric nodes image. Loculated ascites was also present (not shown). This patient’s reactivated TB with TB peritonitis was first acquired in his native country.
image
(Left) Spot film from a small bowel follow-through in a 25-year-old immigrant from India shows deformity of the terminal ileum image and cecum image, with asymmetric thickening and stiffening of the bowel walls, ultimately found to represent TB.

image
(Right) Coronal CECT in an immigrant patient demonstrates asymmetric thickening image of the cecum, which has a cone-shaped appearance in a patient with tuberculous colitis.

TERMINOLOGY

Abbreviations

• Tuberculosis (TB)

Definitions

• Infection by Mycobacterium tuberculosis

IMAGING

General Features

• Best diagnostic clue

image Most common sites of involvement in abdomen are lymph nodes, GU tract, peritoneum, and GI tract

– Abdominal lymphadenopathy most common (2/3 cases)
– GU tract is most common organ system involved
– Any abdominal/pelvic organ or structure may be involved

image Liver, spleen, biliary tree, pancreas, and adrenal glands unusual and more likely in HIV patients or patients with miliary TB

Imaging Recommendations

• Best imaging tool

image CECT

Radiographic Findings

• Often no evidence of lung disease (CXR or CT can be normal)
• Lymphadenopathy (tuberculous lymphadenitis)

image Can range from increased number of normal-sized nodes to massively enlarged conglomerate nodal masses

– Mesenteric and peripancreatic lymph nodes most commonly involved
– Multiple groups often affected simultaneously
image Enlarged, necrotic nodes with hypoattenuating centers and hyperattenuating enhancing rims on CT (40-60%)

– Characteristic of caseous necrosis
– Mixed attenuation nodes are also possible
image Nodes calcify with healing: TB probably most common cause of mesenteric nodal calcification
• Tuberculosis peritonitis

image 3 imaging patterns: Wet, dry, and fibrotic fixed

– Wet type: Large amount of free or loculated ascites

image Higher than water density due to protein/cellular content
image Complex ascites with septations or fibrinous strands
– Dry type: Mesenteric and omental thickening, fibrous adhesions, and caseous nodules
– Fibrotic fixed: Discrete masses in omentum with matted loops of bowel ± loculated ascites
image CT is ∼ 69% sensitive for TB peritonitis

– Difficult to distinguish from carcinomatosis
– Carcinomatosis more likely to demonstrate discrete implants or omental caking
• Gastrointestinal tuberculosis

image Ileocecal region affected in 90% of cases

– Common site due to presence of lymph tissue and stasis of bowel contents in that location
– Cecum and terminal ileum are usually contracted (cone-shaped cecum) with asymmetric wall thickening of ileocecal valve and medial cecum

image Ileocecal valve is “gaping”
– Strictures, regional inflammation common
– Regional lymphadenopathy with central caseation
image Involvement of stomach and proximal small bowel is rare

– Stomach: Affects antrum and distal body, often simulating peptic ulcer disease
– Duodenum: Wall thickening and luminal narrowing
– Any portion of GI tract can be theoretically involved
• Hepatosplenic tuberculosis

image Micronodular pattern

– Innumerable 0.5–2.0 mm nodules may or may not be discretely visualized (most often hypodense on CT and hyperechoic on US)
– May simply appear as hepatomegaly on CT
image Macronodular pattern

– CT

image Acute: Hypoattenuating nodules with ill-defined enhancing margins
image Chronic: Tuberculomas often calcify
image TB and histoplasmosis are most common causes of calcified granulomas
– MR

image T1WI: Hypointense, minimally enhancing, honeycomb lesions
image T2WI: Hyperintense with less intense rim relative to surrounding liver
image Rim enhancement on post-gadolinium images
• Adrenal tuberculosis

image Unilateral (10%) or bilateral (90%)

– Predisposition for bilateral involvement since spread to adrenals usually hematogenous
image Acute: Enlarged adrenals (often appear as discrete centrally necrotic adrenal masses)
image Chronic: Small adrenals with dots of calcification and low signal on all MR sequences
image May cause adrenal insufficiency (most common cause in developing countries)
• Renal tuberculosis

image 75% unilateral
image CT findings

– Most common CT finding is renal calcification (50%)

image Affected part of kidney often nonfunctional; global nonfunction and calcification = “putty” kidney
– Papillary necrosis early finding (usually upper pole)
– Focal wedge-shaped areas of low attenuation, multiple small hypodense nodules, or discrete renal abscess
– Urothelial thickening, caseous debris, and strictures of calyces and infundibuli may lead to hydronephrosis
image Intravenous urography: “Moth-eaten” calyx due to erosions and progression to papillary necrosis

– Strictures of renal pelvis and infundibula
– Caliectasis and hydronephrosis with irregular margins and filling defects due to caseous debris
– Irregular pools of contrast due to parenchymal cavitation
• Ureteral tuberculosis

image Usually secondary to renal TB
image Thickened wall of ureter with strictures most common in distal 1/3 of ureter
image Hydronephrosis and hydroureter can occur upstream
image Corkscrew/beaded ureter due to chronic fibrotic strictures
• Bladder tuberculosis

image Decreased bladder volume with wall thickening, ulceration, and filling defects
image Severe: Scarring → small, irregular, calcified bladder
• Female genital tuberculosis

image Most commonly involves fallopian tubes (in 94% of cases)

– Bilateral salpingitis with strictures ± occlusion
– Tubo-ovarian abscess
– Can result in infertility
image Can involve endometrium resulting in deformed, irregular endometrium on US
• Male genital tuberculosis

image Affects seminal vesicles or prostate gland, rarely testes
image Can resemble a pyogenic abscess ± calcification
• Pancreatic tuberculosis

image Appears as mass mimicking cancer (caseated peripancreatic nodes involving pancreas)

– US: Well-defined hypoechoic lesions
– CT: Hypodense mass (usually pancreatic head) typically without pancreatic duct dilatation or vascular invasion

DIFFERENTIAL DIAGNOSIS

Peritonitis

• Nontuberculous peritonitis
• Peritoneal metastases and lymphoma
• Mesothelioma

Miliary Hepatic Lesions

• Hepatic metastases and lymphoma
• Hepatic opportunistic infection
• Sarcoidosis

Macronodular Hepatic Lesions

• Hepatic metastases and lymphoma
• Hepatic pyogenic abscess
• Primary hepatic malignancy

Ileocecal Lesions

• Amebiasis
• Crohn disease
• Primary cecal malignancy

Lymphadenitis

• Metastases or lymphoma
• Whipple disease
• Mycobacterium avium-intracellulare infection

Renal Lesions

• Renal papillary necrosis
• Renal transitional cell carcinoma
• Other infections 

image (e.g., pyelonephritis, xanthogranulomatous pyelonephritis)

Adrenal Lesions

• Adrenal metastases and lymphoma
• Primary adrenal neoplasm
• Adrenal hemorrhage

Bladder Lesions

• Bladder schistosomiasis
• Cytoxan cystitis
• Radiation-induced bladder calcification
• Calcified bladder carcinoma
• Encrusted foreign materials

PATHOLOGY

General Features

• Etiology

image Primary infection from M. tuberculosis
image Ileocecal region often affected likely due to high density of lymphoid tissue
image Abdominal TB is usually secondary to pulmonary TB

– CXR normal in 2/3 of patients with abdominal TB
– Only 15% have active pulmonary disease
image Other sources of abdominal infection with TB

– Swallowing infected material

image Drinking unpasteurized milk can result in  Mycobacterium bovis  infection
– Hematogenous spread from active or latent infection
– Direct extension from infected tissues

Microscopic Features

• Caseating granulomas are characteristic
• Microscopy and culture for mycobacteria

CLINICAL ISSUES

Presentation

• Most common signs/symptoms

image Abdominal TB often presents with fever, weight loss, and abdominal pain
image Negative chest radiograph or negative tuberculin skin test does not exclude extrapulmonary TB

– May or may not have evidence of pulmonary TB
– May or may not have positive tuberculin test

image Possibly negative in immunosuppressed, malnourished, or severe disseminated disease
• Other signs/symptoms

image Peritonitis is most common clinical manifestation of abdominal tuberculosis

– Affects 1/3 of patients; 90% with ascites (wet type)
image Adrenal tuberculosis

– Addisonian presentation (adrenal insufficiency, hypotension, and electrolyte disturbances)
image Gastrointestinal TB

– Usually few or no symptoms (partial obstruction)

Demographics

• Epidemiology

image Resurgence of TB

– ↑ in immunocompromised patients (especially those with AIDS)
– Drug-resistant strains of M. tuberculosis
– Increasing use of immunosuppressive drugs
– Estimated 1/3 of world population infected with TB
• Risk factors for TB

image Immunocompromise (AIDS, transplant recipients, immunosuppressive drugs)
image Poverty, homelessness, alcoholism, immigration from developing country, imprisonment

Natural History & Prognosis

• Miliary TB

image Recovery is uncommon (< 10%)

Treatment

• Surgery for emergent presentations
• 6-9 month course of multidrug antituberculous chemotherapy

image Most commonly used drugs include rifampin, isoniazid, pyrazinamide, and ethambutol
image Exact drug regimen may vary based on resistance patterns

image
(Left) Axial CECT in a young woman with AIDS demonstrates mesenteric and retroperitoneal lymphadenopathy. Some of the enlarged nodes have a caseated or low-density centrally necrotic appearance image characteristic of mycobacterial infection.
image
(Right) Axial CECT shows a large, complex cystic mass image in the porta hepatis and pancreatic head region, representing conglomerate caseated, enlarged nodes due to Mycobacterium tuberculosis infection.
image
(Left) Axial CECT shows cavitary image and multilobar bronchoalveolar infection of the lungs, typical of active tuberculosis. This patient was a young female college exchange student from Asia.

image
(Right) Axial CECT in the same patient shows mural thickening of the cecum image, along with regional mesenteric lymphadenopathy image typical of intestinal and nodal involvement by TB.
image
(Left) Axial CECT show a small, nonfunctional, and partially calcified “putty” kidney image, typical of chronic TB infection of the kidney. The patient had a known history of pulmonary TB.

image
(Right) Axial NECT shows calcification from healed TB granulomas within retroperitoneal and retrocrural nodes image. The left kidney image is totally calcified and nonfunctional, an autonephrectomy or “putty” kidney due to chronic renal TB. Small focal calcifications were also present in the adrenals.
image
Axial CECT shows large, complex cystic mass image in the porta hepatis and pancreatic head region, representing caseated, enlarged nodes due to M. tuberculosis infection.

image
Axial NECT shows calcification from healed TB granulomas within retroperitoneal nodes image.
image
Axial CECT shows calcification from healed TB granulomas within retroperitoneal nodes image. The left kidney image is totally calcified and nonfunctional, representing an “autonephrectomy” due to chronic renal TB.

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