Miliary tuberculosis (miliary TB, MTB)
Miliary tuberculosis describes lympho‑haematogenous dissemination of Mycobacterium tuberculosis producing numerous tiny granulomatous nodules in multiple organs. It is uncommon (≈1-2% of TB cases) but carries substantial mortality (reported 10-30% despite treatment). Early recognition, prompt specialist involvement and immediate public‑health actions are essential.
Epidemiology and prognosis
- Miliary TB occurs after haematogenous seeding from a primary or reactivated focus and preferentially involves highly perfused organs (lungs, bone marrow, spleen, liver, adrenals, kidneys, brain).
- Prognosis depends on host factors (age, immunosuppression), delay to therapy and central nervous system (CNS) involvement; mortality remains significant even with treatment.
Pathogenesis and common sites
- Dissemination via lympho‑haematogenous routes produces innumerable 1-4 mm granulomatous nodules in affected organs.
- Commonly involved organs and effects:
- Lungs: diffuse parenchymal disease, may cause cough, dyspnoea and hypoxaemia.
- Bone marrow: infiltration may cause anaemia, leucopenia or pancytopenia.
- Liver and spleen: hepatosplenomegaly.
- Adrenals: possible adrenal insufficiency.
- CNS: tuberculous meningitis or encephalitis.
Clinical presentation
- Presentation is protean and often nonspecific. Common features include: