Miliary Tuberculosis

A chest radiograph of a 37-year-old woman shows innumerable tiny nodules throughout both lungs in a uniform, symmetric distribution. 

Axial chest CT image confirms the presence of innumerable micronodules in a random distribution and uniformity.

Facts: Miliary TB

• Acute disseminated infection of mycobacterium tuberculosis via bloodstream, or progression of active TB (rupture of caseating lymph node or cavity into blood vessel)
• Primary site may be intra- or extrapulmonary, or may not be recognizable
• Life-threatening infection. Mortality 13-50%
• Any age, any immune status but poor immune individuals are at increased risk
• Only 30% have positive sputum examination
• Up to 60% have negative skin test

Imaging

• Chest radiograph (CXR) can be normal in early disease 
• CXR usually shows abnormality up to 10 days or more after clinical illness has started. CT can show it earlier
• "Miliary" nodules are tiny (<2 mm), discrete, about the same size. They may coalesce into patchy and more irregular opacities
• Nodules may take 2-3 months to fade even with adequate therapy
• No correlation between number or size of nodules and clinical health
• Lymph node enlargement, hepatosplenomegaly may be seen

Reference:

Palmer PES, Wambani SJ, Reeve P. The imaging of tuberculosis: with epidemiological, pathological, and clinical correlation, 2001.