A total of 619 studies were identified, of which 45 were retrieved for full-text review. Only 27 of those, published between 1997 and 2012, met the inclusion criteria.6,8‐33Table 2 summarizes the design, participants, and findings of the initially selected studies. Subsequently, 12 studies with a high risk of bias based on the QUADAS-2 tool9,12,14,17‐19,22‐24,26,28,31 and another, which was the sole remaining study based on a dual time-point technique21 were excluded (Fig 1). Consequently, only 14 studies entered the final analysis, of which four were prospective,16,20,25,32 five were retrospective,6,15,27,29,30 and five had an unrevealed design.8,10,11,13,33 These eligible studies comprised 639 patients (66% male patients) with a median age of 62 years, of whom 407 (64%) eventually had malignant effusions (or thickening) and 232 had benign pleural conditions. Specifically, the causes of the malignant pleural effusions included 156 MPMs (98 epithelial, 20 sarcomatoid or mixed, and 38 nonspecified) and 251 pleural metastases, either from lung cancer (135 non-small cell histology, seven small-cell, and 27 nonspecified), nonspecified origin (n = 59), or miscellaneous (n = 23). No data on the precise etiology were reported in 76 cases (33%) of benign effusions or thickening, whereas the remaining ones were attributed to nonspecific pleuritis (n = 40), parapneumonic/empyema (n = 49), benign asbestosis (n = 22), fibrosis (n = 23), TB (n = 13), and benign tumors (n = 9).