To evaluate the clinical manifestation and radiographic findings of pulmonary cryptococcosis in the immunocompetent patients in order to improve its early diagnosis and early treatment.

A total of 47 immunocompetent patients with pathologically-proven pulmonary cryptococcosis after surgery or biopsy admitted to Tangdu Hospital affiliated to Air Force Military Medical University from January 2006 to October 2018 were included. The patients′clinical symptoms and CT imaging features were reviewed retrospectively.

Pulmonary cryptococcosis occurred in the immunocompetent patients predominately in the middle-aged and elderly patients who were 40-60 years old (85.10%), but it had no specific clinical symptoms. The CT imaging features included single pulmonary nodule/mass (48.94%), multiple nodules/masses (19.15%), pneumonia-like infiltration(23.40%), mixed manifestations (6.38%), and atypical imaging features (2.13%). Typical CT imaging features were often accompanied by "halo sign" , "flat margin sign" , "pleural indentation sign" , "spicule sign" , "mushroom brother sign" , and "proximal air bronchogram sign" . Among the three types of radiographic features including single pulmonary nodule/mass, multiple nodules/masses and pneumonia, the "halo sign" , "flat sign" , "pleural indentation sign" and "spicule sign" were more common in the first two types, with statistical significant difference (78.26%, 66.67% and 27.27%, respectively, P=0.019; 82.61%, 77.78% and 18.18%, respectively, P=0.001; 56.52%, 44.44% and 0%, respectively, P=0.003; and 39.13%, 33.33% and 0%, respectively, P=0.037). The "proximal air bronchogram sign" was significantly more frequently observed in the pneumonia type (34.78%, 33.33% and 81.82%, P=0.029), while the "mushroom brothers sign" was predominantly observed in the multiple nodules/masses (77.78%).

Pulmonary cryptococcosis in the immunocompetent patients has no specific clinical symptoms. The chest imaging features of pulmonary cryptococcosis in the immunocompetent patients are different from the immunocompromised patients. However, they are often confused with pneumonia, tuberculosis, and lung cancer, etc. "Halo sign" , "mushroom brother sign" and "proximal air bronchogram sign" are relatively specific to the diagnosis of pulmonary cryptococcosis.