Case 1004
Pleural effusionWhat is the diagnosis?
Answer hidden. Review the images and history, decide on your diagnosis, then reveal.
Findings
- Homogeneous basal opacity with a concave, meniscus-shaped upper border rising laterally
- Loss of the costophrenic angle and hemidiaphragm outline on the affected side
- On the lateral view the fluid fills the posterior costophrenic recess
- The decubitus film shows fluid moving to the dependent side — the effusion is free-flowing
Case discussion
The meniscus sign is characteristic of free pleural fluid. The lateral view is more sensitive than the frontal view because the posterior costophrenic recess is the lowest part of the pleural space.
Ultrasound is the best next test: it confirms fluid, shows septations and guides diagnostic aspiration. Fluid analysis with Light's criteria separates transudates from exudates and directs the search for a cause.
