From the Guidelines
Ultrasound findings in malignant pleural effusion typically include pleural thickening, pleural nodularity, and diaphragmatic thickening, which are highly suggestive of malignancy, as reported in the most recent and highest quality study 1. The most relevant ultrasound findings in malignant pleural effusion are:
- Pleural thickening greater than 1 cm
- Pleural nodularity
- Diaphragmatic thickening exceeding 7 mm
- Presence of hepatic metastases in cases of right-sided effusions These findings are highly suggestive of malignancy, but definitive diagnosis requires cytological examination of the pleural fluid or pleural biopsy, as no single ultrasound feature is pathognomonic for malignant pleural effusion 1. The use of thoracic ultrasound (TUS) is now an essential tool in the diagnosis and management of pleural effusions, and it should be performed on every patient at their initial presentation and again whenever a pleural procedure is being performed 1. It's worth noting that the sensitivity and specificity of TUS findings for malignant pleural effusion have been debated in the literature, with some studies suggesting that pleural thickening has low sensitivity and variable specificity, and only visceral or parietal nodularity is specific for malignant pleural disease with a high positive predictive value 1. However, the most recent and highest quality study 1 supports the use of TUS in the diagnosis and management of malignant pleural effusion, and its findings should be prioritized in clinical practice.
From the Research
Ultrasound Findings in Malignant Pleural Effusion
The ultrasound findings in malignant pleural effusion include:
- Loss of lung sliding
- Visceral pleural thickening
- Pleural nodularity These findings are supported by various studies, including 2, which analyzed the ultrasound characteristics of confirmed malignant pleural effusion, and 3, which evaluated the utility of ultrasound features in predicting malignancy in undiagnosed pleural effusions.
Diagnostic Value of Ultrasound
The diagnostic value of ultrasound in malignant pleural effusion is significant, with studies showing that it can aid in differentiating malignant from benign pleural disease. For example, 4 found that thoracic ultrasound correctly diagnosed malignancy in 26/33 patients, with a sensitivity of 73% and specificity of 100%. Similarly, 3 found that ultrasound had an overall sensitivity of 80.3% and specificity of 83.6% for the detection of malignancy.
Ultrasound Characteristics
The ultrasound characteristics that are suggestive of malignant pleural effusion include:
- Pleural thickening >1 cm
- Pleural nodularity
- Diaphragmatic thickening >7 mm
- Swirling sign
- Absence of air bronchograms These characteristics are supported by studies such as 3 and 4, which found that they were significantly more common in malignant pleural effusions than in benign ones.
Clinical Implications
The clinical implications of these findings are that ultrasound can be a useful adjunct in the diagnostic pathway of malignant pleural effusion, particularly in patients with suspected malignant disease. As noted in 5, thoracic ultrasound is useful in identifying diaphragmatic or pleural thickening and nodularity, which can aid in the diagnosis of malignant pleural effusion. Additionally, 6 found that ultrasonic-assisted thoracoscopy can be a valuable tool in the diagnosis of pleural disease, particularly when less invasive methods have not yielded a diagnosis.