What entity can result in fat low attenuation pulmonary opacities on CT?
Lipoid pneumonia. This occurs after aspiration of fatty substances such as those that contain mineral oil or petroleum jelly and is often asymptomatic, although sometimes it is associated with cough or dyspnea. On imaging, focal or multifocal alveolar opacities are seen, most often in the lower lobes, often perihilar in distribution. Sometimes, they may appear masslike with irregular margins, potentially mimicking lung cancer, and may be surrounded by ground glass opacities. Characteristic fat (or near fat) low attenuation components, when present, are highly suggestive of the diagnosis.