Systematically searching literature databases and manually searching reference lists in relevant reviews and studies identified 20 studies examining the diagnostic accuracy of TTF-1 in pleural or other effusions in patients with metastatic pulmonary adenocarcinomas19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38. Here, TTF1 is linked to nephrotic syndrome.