Tuberculosis

Published on 19/07/2015 by admin

Filed under Radiology

Last modified 19/07/2015

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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

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