From the Research
The typical appearance of a chest X-ray in patients with fat embolism syndrome shows diffuse, bilateral, patchy alveolar infiltrates that develop within 24-48 hours after the initial injury, often with a "snowstorm" or "ground-glass" appearance distributed throughout both lung fields 1. These infiltrates represent areas of noncardiogenic pulmonary edema resulting from fat droplets lodging in the pulmonary microvasculature, causing inflammation, endothelial damage, and increased capillary permeability, allowing fluid to leak into the alveolar spaces. The radiographic findings may be disproportionately mild compared to the patient's clinical symptoms of hypoxemia. Importantly, the chest X-ray may initially be normal in the early stages of fat embolism syndrome, with radiographic abnormalities developing hours after the onset of respiratory symptoms. The infiltrates typically resolve within 1-2 weeks if the patient recovers. CT scans are more sensitive than plain radiographs and may show these changes earlier, appearing as areas of ground-glass opacification with or without interlobular septal thickening, as described in a study published in Respiratory medicine 2. Some studies have also reported ill-defined centrilobular and subpleural nodules in addition to ground-glass opacities and consolidation on computed tomography scans of the chest in patients with fat embolism syndrome 3. However, the most recent and highest quality study, published in Frontiers in medicine in 2023, supports the typical appearance of a chest X-ray in patients with fat embolism syndrome as described above 1. Key points to consider when evaluating a chest X-ray in a patient with suspected fat embolism syndrome include:
- Diffuse, bilateral, patchy alveolar infiltrates
- "Snowstorm" or "ground-glass" appearance
- Noncardiogenic pulmonary edema
- Infiltrates may be disproportionately mild compared to clinical symptoms
- CT scans may be more sensitive than plain radiographs.