[The so-called malignant pleural effusion: a new review of direct data obtained with diagnostic pleuroscopy]

We analyze a series of 896 thoracoscopies for pleural effusion, of which 78% (662/896) were due to pleural carcinomatosis, primary or metastatic. Pleural malignancy was observed mainly, in the right hemithorax (65%), arising from tumors within the diaphragm. The likelihood of finding pleural metastasis in lung cancer was 77%. When the pleural effusion is slight (less than 500 ml) the likelihood falls to 22%. We therefore advise thoracoscopy in the former and thoracotomy in the latter. Blood-stained effusion continues to have the worst prognosis (84% stemming from metastasis) and signifies an advanced stage of pleural metastasis. The pleura parietal is involved in 69% of pleural carcinomatosis cases, and in 80% when the lower hemithorax or the area around breast or lung tumors are involved. The cytology yield was 45.9%, though always depending on extent of metastasis. When metastasis was slight, the likelihood of positive cytology was less (19%) and when metastasis was generalized throughout the entire pleura the likelihood increased to 73%. We found no reason to think that the cells in most pleural liquids are able to nest and form tumoral niches. The origin of such cell nests was rather found to be in shedding from the metastases themselves, from lung tumors or from carcinomatous lymphangitis by lymphatic obstruction. The diagnostic yield of thoracoscopy once again proved to be superior to that of pleural biopsy.