Regarding IgG4-related pleural effusion, a previous review of 8 cases showed slightly elevated pleural fluid ADA levels, with a median of 32.2 U/L (range 26.6–50.1), which was significantly higher than that in non-IgG4-related cases without tuberculous pleurisy (P = .05).[4] Considering that ADA levels are elevated in both IgG4-related pleural effusion and tuberculous pleurisy, it is very important to distinguish between them because of the different treatments. Here, ADA is linked to Pleural effusion.