Silicosis CT

• High resolution computed tomography (HRCT) is helpful for patients with an atypical clinical presentation or atypical findings on chest radiograph. A baseline HRCT scan in patients with radiographic findings of silicosis is usually obtained to document the presence and extent of nodules, emphysema, and other silica-related abnormalities that may progress in the future.

• A CT scan can also provide a mode detailed analyses of the nodules, and can reveal cavitation due to concomitant mycobacterial infection. In the diagnosis of silicosis, HRCT scans are superior to chest X-rays, both for the early detection of the initial phases of the disease and for the identification of PMF.^[1]
• The typical HRCT findings in simple silicosis are

• Bilateral,
• Symmetric,
• Centrilobular, and perilymphatic nodules
• With sharp margination.
• These nodules calcify in 10 to 20 percent of patients.

• However, HRCT is usually not necessary in simple silicosis unless fever or atypical radiographic features such as spiculated nodules, a single nodule of substantially larger size than the others are noted ^[2][3].
• In complicated silicosis HRCT is superior to conventional chest radiography for documentation of conglomerate lesions and emphysematous changes. The HRCT findings consist of

• Numerous bilateral centrilobular nodular opacities,
• Focal ground glass opacities, and
• Patchy areas of consolidation ^[4].
• Hilar lymph node enlargement may be apparent on HRCT, which is a typical feature of silicosis, but not of pulmonary alveolar proteinosis.

• In a small series that compared pulmonary alveolar proteinosis (PAP) and acute silicosis, the most common HRCT finding in PAP was “crazy paving”, while the most common finding in acute silicosis was dependent consolidation and nodular calcification^[5].
• Although pleural effusions are unusual in silicosis, pleural thickening appears to be common among patients with more severe disease^[6].

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