Miliary tuberculosis is a rare form of tuberculosis characterized by the widespread dissemination of tuberculosis bacteria through the bloodstream, forming small nodules throughout the body. It represents 1-3% of tuberculosis cases. Risk factors include age, immunosuppression, cancer, HIV, malnutrition, and diabetes. The bacteria spread from the lungs into the bloodstream and infect multiple organs. Symptoms are nonspecific and include weakness, fever, weight loss, and cough. Diagnosis involves imaging tests to identify the small nodules and laboratory tests such as sputum cultures. Treatment requires a multi-drug regimen for 6-9 months.

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