Differentials
Pleural thickening
SIGNS / SYMPTOMS
Patient has a history of prior pleural disease such as tuberculosis or empyema, or exposure to environmental agents.
INVESTIGATIONS
Thickened pleura from pleural fibrosis resulting from previous pleural inflammation or prior environmental exposures, such as asbestos, beryllium, or silica, can appear similar to a pleural effusion on chest x-ray. Ultrasound and CT distinguish fluid from thickening alone.
Pulmonary collapse and consolidation
SIGNS / SYMPTOMS
History to support a possible underlying cause, such as haemoptysis and weight loss in lung cancer.
INVESTIGATIONS
Can occur in conjunction with pleural effusion through compression, or can be mistaken for a pleural effusion on chest x-ray. CT scan or ultrasound can help to define the difference between lung collapse, consolidation, and mass lesions from effusions.
Elevated hemidiaphragm
SIGNS / SYMPTOMS
Can result from paralysis of the phrenic nerve.
Paradoxical chest movement during the respiratory cycle can be a clue to diagnosis.
INVESTIGATIONS
A fluoroscopic test, or ultrasound, to analyse diaphragmatic movement with rapid breathing (often called a 'sniff test') can evaluate diaphragm paralysis.
Pleural tumours/extrapleural fat
SIGNS / SYMPTOMS
Extrapleural fat is asymptomatic.
INVESTIGATIONS
The density of fat is much lower than that of fluid on CT scan and should be readily differentiated.
Pleural tumours can also be easily demonstrated on CT.
The presence of nodularity is often key to a malignant process.[63]
Coronavirus disease 2019 (COVID-19)
SIGNS / SYMPTOMS
Close contact with a confirmed or probable case of COVID-19, in the 14 days prior to symptom onset.
See our COVID-19 topic for further information.
INVESTIGATIONS
Real-time reverse transcription polymerase chain reaction (RT-PCR): positive for SARS-CoV-2 RNA.
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