Differential Diagnosis for Focal Hypolucency in Lung
- Single most likely diagnosis + Pulmonary consolidation (e.g., pneumonia): This is the most common cause of focal hypolucency in the lung, often resulting from infection or inflammation that fills the airspaces with exudate, making the area appear more opaque on imaging.
- Other Likely diagnoses + Pulmonary edema: Fluid accumulation in the lungs, often due to heart failure, can cause focal or diffuse hypolucency. + Pulmonary hemorrhage: Bleeding into the lung tissue can lead to areas of increased density. + Lung abscess: A localized collection of pus within the lung, often appearing as a cavity with an air-fluid level. + Pulmonary infarction: Dead lung tissue due to lack of blood supply, which can appear as a focal area of hypolucency.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.) + Pulmonary embolism with infarction: While not always visible as a focal hypolucency, a large pulmonary embolism can cause infarction, which might appear this way. + Tumor (primary or metastatic): Although less common, a tumor can present as a focal area of increased density, especially if it is large or if there is associated hemorrhage or necrosis.
- Rare diagnoses + Pulmonary alveolar proteinosis: A rare condition characterized by the accumulation of surfactant-like protein and phospholipids in the alveoli, leading to diffuse or focal hypolucency. + Lymphoproliferative disorders (e.g., lymphoma): Can cause focal or diffuse lung involvement, appearing as areas of increased density. + Sarcoidosis: Although typically presenting with hilar lymphadenopathy and diffuse lung disease, sarcoidosis can rarely cause focal lung lesions. + Eosinophilic pneumonia: A rare condition characterized by the infiltration of eosinophils into the lung tissue, which can cause focal or diffuse areas of increased density.