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Findings: The frontal chest radiograph shows widespread 1-3 mm nodules throughout the lungs. The high resolution chest CT shows multiple, randomly distributed 1-3 mm nodules throughout the lungs.
Diagnosis: Miliary tuberculosis.
Discussion: The differential of miliary nodules is long, and includes tuberculosis and histoplasmosis, silicosis, metastatic disease, EG and sarcoid. In an older nursing home patient with fever and weight loss, tuberculosis must be a primary consideration. Miliary tuberculosis is an uncommon manifestation of tuberculosis, and represents hematogenous dissemination of the organism. Miliary TB can be missed on plain radiographs due to the small size of the nodules; HRCT may be important in establishing its diagnosis. It can be a difficult diagnosis to make, as in older patients, the TB skin test may be negative due to anergy.
It is helpful in the HRCT evaluation of nodules to establish their distribution. Random nodules are most commonly seen in metastatic disease, silicosis and miliary infection. A hypersensitivity pneumonitis or bronchiolitis obliterans. A peribronchiolar pattern may favor sarcoidosis. In this patient, the clinical history and random distribution of miliary nodules favored miliary tuberculosis.
References:
Armstrong: Imaging of Diseases of the Chest, Mosby, Philadelphia 1996, p183.
Webb WR, Muller NL, Naidich DP. HRCT of the Lung, New York 1996, Raven Press.
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