Although Meigs’ syndrome is regarded as a well-defined entity, contradictory data on pleural fluid characteristics have been presented, with some papers classifying it as a transudate, whereas others stating that it is an exudate.The aims of the study were: (1) to evaluate pleural fluid characteristics in patients with Meigs’ syndrome and (2) to analyze the prevalence of transudative and exudative pleural effusion in relation to the applied definition of the syndrome.We performed a search through medical databases (MEDLINE, EMBASE, SCOPUS, and GOOGLE SCHOLAR) to identify papers on Meigs’ syndrome published between 1940 and 2013. Two authors independently reviewed each paper searching for prespecified data: (1) signs and symptoms, (2) tumor characteristics, (3) clinical and laboratory data on ascites, (4) clinical, radiological, and laboratory data on pleural fluid, (5) clinical course after tumor removal. All case reports were reclassified according to a new unequivocal classification of Meigs’ syndrome-related entities.A total of 653 papers were initially identified, and 454 articles reporting 541 patients were included in the final analysis. After reclassification according to our case definitions, there were 196, 113, and 108 patients defined as classic Meigs’ syndrome, nonclassic Meigs’ syndrome, and pseudo-Meigs’ syndrome, respectively. Significantly more patients presented with right-sided than left-sided and bilateral pleural effusions (P < 0.001). Median volume of withdrawn pleural fluid was 2950 (1500–6000) mL. The classification of pleural effusion with the use of Light's criteria was possible in only 7 patients. In 6 of these patients pleural effusion met the criteria for an exudate. When the protein concentration > 3.0 g/dL was applied as a criterion of pleural exudate, 88.8% (80/90) of effusions were classified as exudates. Increasing the cut-off level to 3.5 g/dL resulted in only a modest decrease in the percentage of exudative effusions (81%, 73/90).Surprisingly few reports on Meigs’ syndrome present data reliably defining the character of pleural effusion. The available data indicate, however, that the majority of pleural effusions in patients with this entity are exudates. This finding may be a prerequisite for the verification of some earlier presented concepts.

Due to the paucibacillary nature of tuberculous pleural effusion the diagnosis of pleural tuberculosis is challenging. This prospective study was undertaken to evaluate the diagnostic performance of ten different pleural fluid biomarkers in the differentiation between tuberculous and non-tuberculous pleural effusions. Two hundred and three patients with pleural effusion (117 men and 86 women, median age 65 years) were enrolled. Routine diagnostic work-up, including thoracentesis and pleural fluid analysis, was performed to determine the cause of pleural effusion. The following biomarkers were measured in pleural fluid: adenosine deaminase (ADA), interferon gamma (IFN-γ), interleukin 2 soluble receptor (IL-2sRα), sub-unit p40 of interleukin 12b (IL-12p40), interleukin 18 (IL-18), interleukin 23 (IL-23), IFN-γ induced protein 10 kDa (IP-10), Fas-ligand, human macrophage-derived chemokine (MDC) and tumor necrosis factor alfa (TNF-α). There were 44 (21.7%) patients with tuberculous pleural effusion, 88 (43.3%) patients with malignant pleural effusion, 35 (17.2%) with parapneumonic effusion/pleural empyema, 30 (14.8%) with pleural transudates, and 6 (3%) with miscellaneous underlying diseases. Pleural fluid IFN-γ was found the most accurate marker differentiating tuberculous from non-tuberculous pleural effusion, with sensitivity, specificity, PPV, NPV, and AUC 97%, 98%, 95.5%, 99.4%, and 0.99, respectively. Two other biomarkers (IP-10 and Fas ligand) also showed very high diagnostic accuracy with AUC≥0.95. AUC for ADA was 0.92. We conclude that IFN-γ, IP-10, and Fas-ligand in pleural fluid are highly accurate biomarkers differentiating tuberculous from non-tuberculous pleural effusion.

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