Abstract: Objective To evaluate the diagnostic value of pulmonary cryptococcosis (PC) for serum cryptococcal capsule polysaccharide antigen (CrAg) detection, ultrasound-guided transbronchial lung biopsy (EBUS-TBLB) and CT-guided percutaneous lung biopsy, and to analyze the affecting factors. Methods From January 2015 to December 2020, 41 patients diagnosed pathologically with PC in Southeast University Zhongda Hospital were analyzed retrospectively;serum CrAg detection was performed in all patients. Results Among the 41 patients, 32 patients underwent EBUS-TBLB and 16 were confirmed PC, the sensitivity was 50%(16/32), 23 patients underwent CT-guided percutaneous lung biopsy and 22 were diagnosed, with the sensitivity 95.7%(22/23), while 3 were comfirmed by surgery; 29 cases were positive for CrAg detection in the 41patients (sensitivity of 70.7%), while the sensitivity could be increased to 96.9% combined with EBUS-TBLB; Imaging features had no significant effect in the diagnosis of PC for EBUS-TBLB. Patients had wider lesions of the lung and had immune suppression, whose sensitivity of serum CrAg detection in PC was higher. Conclusions CT guided percutaneous lung biopsy has more advantages in the diagnosis of PC; combined with EBUS-TBLB and serum CrAg detection can significantly improve the sensitivity , and serum CrAg detection has a good sensitivity when the range of lung lesions were wide and patients were in immunosuppression.

Key words: pulmonary cryptococcosis, serum cryptococcal capsule polysaccharide antigen detection, ultrasound-guided transbronchial lung biopsy, CT-guided percutaneous lung biopsy