Tuberculosis, Miliary

Tuberculosis, Miliary

Martha Huller Maier, MD

Axial HRCT in this patient with miliary tuberculosis shows innumerable miliary nodules image, which have a random pattern of distribution.

Axial HRCT in the same patient more inferiorly shows miliary nodules image uniformly distributed throughout the lung.


Abbreviations and Synonyms

  • Tuberculosis (TB), miliary TB, disseminated tuberculosis, mycobacteremia


  • Fulminant infection with Mycobacterium tuberculosis disseminated via bloodstream

    • Typically a complication of primary infection with tubercle bacillus

    • Less common in post-primary tuberculosis


General Features

  • Best diagnostic clue

    • Innumerable small noncalcified nodules with random distribution

      • Distinct from endobronchial spread of infection, with tubercle bacillus resulting in tree-in-bud pattern of nodularity

  • Patient position/location

    • Bilateral diffuse random distribution of nodules

    • Mild basilar predominance acutely

    • Mild upper lung zone predominance chronically

  • Size: Nodules < 5 mm diameter

  • Morphology: Fine rounded nodules: May be discrete or less well defined

CT Findings

  • Morphology

    • Nodules small and uniform in size, usually too numerous to count

    • Usually sharply marginated

    • May have background of ground-glass opacities or septal thickening

    • Nodules are diffuse and bilateral

    • May have feeding vessel sign

  • Distribution

    • Random distribution of nodules with respect to secondary pulmonary lobule

      • Not clustered into rosettes like centrilobular disease

    • Profusion of nodules may be higher in lower lung zones acutely

      • Due to increased perfusion of lower lung zones

    • Nodules may grow faster and become larger in upper lung zones with time

      • Due to increased oxygen concentrations in upper lung zones

  • Evolution

    • Resolution complete with proper therapy or restoration of immune competence

  • Associated findings

    • 30% of individuals with miliary disease may have other findings that suggest TB

      • Tuberculoma, lymphadenopathy, consolidation, effusion suggest miliary dissemination as result of primary TB

      • Calcified lymph nodes, cavitation, upper lobe fibrocavitary disease suggest miliary dissemination as result of post-primary TB

Radiographic Findings

  • Tiny nodules in miliary TB are too small (< 3 mm diameter) to be individually visualized radiographically

    • Summation effect: Superimposition of lesions normally too small to be seen on radiographs; nodules summate to miliary pattern

Imaging Recommendations

  • Best imaging tool

    • CT can demonstrate miliary disease before it becomes radiographically apparent

    • Typical miliary lesions may not be visible radiographically until 3-6 weeks after hematogenous dissemination

    • 25-40% of affected individuals have normal chest radiographs at initial presentation



  • Common metastases presenting with miliary pattern

    • Thyroid cancer

    • Melanoma

    • Choriocarcinoma

    • Renal cell carcinoma

    • Breast cancer

  • Metastatic nodules tend to be slightly larger, more well defined than those of miliary tuberculosis

    • Tend to vary more in size than those of miliary tuberculosis

Disseminated Fungal Disease

  • Histoplasmosis: Miliary nodules heal with calcification

Viral Pneumonia

  • Healed varicella pneumonia can present as miliary calcified nodules

Sarcoidosis and Silicosis

  • Miliary pattern of nodularity less common but has been described

  • Nodules predominantly in middle and upper lung

Pulmonary Hemosiderosis

  • Associated with chronic mitral valve stenosis

  • Nodules often calcified/ossified


  • Initial miliary pattern may coalesce to progressive massive fibrosis much like silicosis

  • Nodules may be calcified

Bronchioloalveolar Cell Carcinoma

Sep 20, 2016 | Posted by in RESPIRATORY IMAGING | Comments Off on Tuberculosis, Miliary

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