Miliary Tuberculosis

General Considerations 

• Widespread hematogenous dissemination of Mycobacterium Tuberculosis
• So named because the nodules are the size of millet seeds (1-5mm with a mean of 2 mm)
• Miliary TB represents only 1-3% of all cases of TB
• Older men, African Americans and pregnant women are susceptible
• Considered to be a manifestation of primary TB–although clinical appearance of miliary TB may not occur for many years after initial infection
• When treated, clearing is frequently rapid
  • Miliary TB seldom, if ever, produces calcification
• Under age 5, there is an increased risk of meningitis 

Risk Factors 

• Immunosuppression
• Cancer
• Transplantation
• HIV
• Malnutrition
• Diabetes
• Silicosis
• End-stage renal disease
  

Clinical Findings

• Onset is insidious
• Patients may not be acutely ill
• Symptoms include
  • Fever and weight loss
• Weakness and fatigue
• Chills, night sweats are common
• Cough
• Hemoptysis
• Anorexia
• Hepatomegaly and lymphadenopathy are common
  

Imaging Findings

• Takes weeks between the time of dissemination and the radiographic appearance of disease
• Up to 30% have a normal chest radiograph
• When first visible, they measure about 1 mm in size; they can grow to 2-3mm if left untreated
• Produces innumerable, non-calcified nodules
• High-resolution CT scans are more sensitive at demonstrating small nodules
• Nodules are either sharply or poorly defined
• 1–4-mm in size
• Diffuse, random distribution
• May be associated with intra- and interlobular septal thickening
  

Differential Diagnosis

• Pneumoconiosis, especially silicosis or anthrosilicosis
• Metastatic nodules, especially from thyroid carcinoma
• Sarcoidosis
  

Treatment

• Estimated that up to 50% of cases are undiagnosed antemortem
• Four-drug regimen to start
  • Isoniazid
• Rifampin
• Pyrazinamide
• Ethambutol or streptomycin
• Treatment may continue for 6-9 months
• 9-12 months with meningeal involvement
  

Complications

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

Prognosis

• If not treated, almost 100% fatal
• With treatment, less than 10% mortality

Miliary Tuberculosis. Top. Innumerable, small, millet-seed sized nodules are seen distributed throughout both lungs, shown in close up view below (white circle).
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