Miliary TB

1. Miliary TB
Dr. Mahesh Chaudhary
Phase: A (March 2014)
Radiology & Imaging, BSMMU

2. General Considerations
• Widespread hematogenous dissemination of Mycobacterium tuberculosis
• Nodules are the size of millet seeds (1-4mm, mean 2mm)
• Miliary TB represents only 1-3% of all cases of tuberculosis
• Up to 50% of cases are undiagnosed ante mortem
• Extreme of ages, Immuno-compromised are more susceptible
• Under age 5, there is an increased risk of meningitis
• Seen both in primary and post-primary tuberculosis
• When treated, clearing is frequently rapid

3. Risk Factors
• Age – Child & Elderly
• Immunosuppression
• Cancer
• Transplantation
• HIV
• Malnutrition
• Diabetes
• Silicosis
• End-stage renal disease

4. Pathophysiology of Miliary TB
• Tuberculous infection in the lungs results in erosion of
the epithelial layer of alveolar cells and the spread of
infection into a pulmonary vein
• Bacteria reach the left side of the heart and enter the
systemic circulation, they may multiply and infect extra
pulmonary organs
• Once infected, the cell mediated immune response is
activated. The infected sites become surrounded by
macrophages which form granuloma, giving the typical
appearance of miliary tuberculosis

5. Clinical Findings
• Onset is insidious
• Patients may not be acutely ill
• Symptoms include
 Weakness and fatigue (90%)
 Fever and weight loss (80%)
 Chills, night sweats are common
 Cough, Hemoptysis
 Anorexia
• Hepatomegaly and lymphadenopathy are common

6. Lab Studies for Miliary TB
• CBC - Leukopenia/leukocytosis
• ESR - elevated in approximately 50% of patients
• Lumbar puncture - strongly considered
Lymphocytic predominance (70%)
Elevated protein levels (90%)
Low glucose levels (90%)
Acid-fast bacilli (≥40%)
• Cultures for mycobacteria
• PCR

7. Imaging Findings
• Takes weeks between the time of dissemination and the
radiographic appearance
• Up to 30-50% have a normal chest radiograph
• When first visible, they measure about 1 mm in size; they can
grow to 3-5mm if left untreated
• Produces innumerable, non-calcified nodules
• HRCT scans are more sensitive at demonstrating small nodules
• Bilateral, diffuse, random distribution
• May be associated with intra- and interlobular septal thickening

8. Chest X-Ray
• Typical appearance only in 50% of cases
• Bilateral pleural effusions indicate dissemination.
This may be a useful clue.
• Nodules characteristic of miliary TB may be better
visualized on lateral chest radiography (especially
in the retrocardiac space).
• Nodules are the size of millet seeds (1-5mm,
mean=2mm)

10. Chest CT scanning
• Chest CT scanning has higher sensitivity and
specificity than chest radiography in displaying well-
defined randomly distributed nodules.
• High-resolution CT scanning with 1-mm cuts may
be even better. It is useful in the presence of
suggestive and inconclusive chest radiography
findings.

12. USG
• Ultrasonography may reveal
 Diffuse liver disease
 Hepatomegaly
 Splenomegaly
 Para-aortic lymph nodes
 Minimum pleural effusion

13. Differential Diagnosis

14. Treatment
• Four-drug regimen to start
 Isoniazid
 Rifampin
 Pyrazinamide
 Ethambutol or streptomycin
• Treatment may continue for 6-9 months
• 9-12 months with meningeal involvement

15. Complications
• Dissemination via bloodstream to
 Prostate
 Seminal vesicles
 Epididymis
 Fallopian tubes
 Endometrium
 Meninges
 Lymph nodes
 Liver
 Spleen
 Skeleton
 Kidneys
 Adrenals

16. Prognosis
• If not treated, almost 100% fatal
• With treatment, less than 10% mortality
• Early treatment for suspected TB has been shown to
improve outcome
• The relapse rate is 0-4% with adequate therapy
• Most relapses occur during the first 24 months after
completion of therapy

17. References
• D. Sutton Text book of Radiology & Imaging 7th
Ed
• Haaga CT & MRI of Whole body 5th
Ed
• Davidson’s Internal Medicine 22nd
Ed
• Medscape
• Pubmed Journals
• Radiopedia.org
• LearningRadiology.com