Squalene-induced extrinsic lipoid pneumonia: Serial radiologic findings innine patients

Purpose: The purpose of this work was to demonstrate the initial and follow -up radiologic findings of squalene-induced extrinsic lipoid pneumonia. Method: Follow-up chest radiographs (n = 9) and high-resolution CT scans (n = 3) as well as initial radiographs (n = 9) and CT scans (n = 8) were obta ined in nine patients with squalene-induced extrinsic lipoid pneumonia. The serial radiologic findings were analyzed retrospectively by three chest ra diologists, focusing on the pattern and distribution of parenchymal abnorma lities. Results: The most frequent pattern of parenchymal abnormalities on chest ra diograph was areas of ground-glass opacity (n = 9, bilateral 6), followed b y consolidation (n = 7, bilateral 3) and poorly defined small nodules (n = 4, bilateral 2). The abnormalities were distributed in the right lower lung (n = 9), left lower lung (n = 6), and right middle lung (n = 6) zones, ini tial CT scans (n = 8) demonstrated bilateral areas of ground-glass attenuat ion (n = 8), poorly defined centrilobular nodules (n = 8), crazy paving (n = 6), and consolidation (n = 3). The abnormalities were distributed in the right middle lobe (n = 8) and in both lower lobes (n = 5). Follow-up chest radiograph (n = 9) showed complete disappearance (n = 2) and decrease (n = 7) in the extent of the parenchymal abnormalities. Follow-up CT scans (n = 3) demonstrated decrease (n = 2) and no change (n = 1) in the extent of the abnormalities. Conclusion: Squalene-induced extrinsic lipoid pneumonia most commonly appea rs as areas of ground-glass attenuation mixed with poorly defined centrilob ular nodules and crazy paving on CT, being distributed mainly in the right middle and both lower lobes. The lesions are indolent and remain after cess ation of squalene ingestion.