摘要To the Editor:We appreciate the attentive and interesting article "clinical value of tumor markers for determining cause of pleural effusion" written by Gu et al.[1] The authors have nicely shown the tumor markers in tuberculous pleural effusion (TPE) differ significantly from those in malignant pleural effusion (MPE) especially when detected in pleural fluid,and there is still no single tumor marker with high sensitivity and specificity in differential diagnosis of pleural effusion (such as TPE and MPE);the combined detection of tumor markers can improve diagnostic sensitivity.Therefore,the authors explored the differential diagnostic value of five tumor markers,including carbohydrate antigen 125 (CA 125),carbohydrate antigen 199 (CA199),carcinoembryonic antigen (CEA),neuron-specific enolase (NSE),and squamous cell carcinoma-associated antigen in patients with TPE and MPE.Especially,the discussion section of this article has given readers some inspirations.We can develop new perspectives on the differential diagnosis ofpleural effusion from these three aspects of specimen types,inspection methods,and test items.