What is the key question?

• Unilateral malignant pleural effusion is difficult to definitively diagnose. Many effusions remain cytologically negative despite multiple attempts at diagnosis via drainage. This is particularly the case in mesothelioma.

What is the bottom line?

• Early and simple diagnosis may save patients multiple increasingly complicated investigations, expedite treatment and reduce costs.

Why read on?

• Sensitivity of pleural fluid cytology varies significantly with tumour type. Overall, pleural fluid cytology was diagnostic in 46% of malignancies. Adenocarcinoma, ovarian and breast cancer subtypes are those with the best cytological sensitivity.