Pleural effusion: an "acoustic window" for sonography of pleural metastases.

We report the sonographic findings in 32 patients with malignant disease associated with pleural effusions diagnosed by chest roentgenograms. No tumor lesions were seen in any case on X-ray films. Thoracic sonography, however, detected previously undocumented metastatic disease with diaphragmatic (N = 19), parietal (N = 8), visceral (N = 2) or combined (N = 3) pleural involvement. Additionally, a distinction could be made between nodular lesions (N = 19), sheet-like tumor masses (N = 10), and combined (N = 3) tumor spread. In all cases thoracentesis was performed. Cytology showed malignant cells in 28 patients. Pleural metastasis was histologically confirmed by ultrasound-guided fine needle biopsy in 2 cases. The present study demonstrates the value of scrutinized thoracic sonography in patients with pleural effusion for the detection of pleural metastases.