Pulmonary cryptococcosis: comparison of clinical and radiographic characteristics in immunocompetent and immunocompromised patients.

STUDY OBJECTIVES: We compared the clinical characteristics and imaging findings between immunocompetent and immunocompromised patients in whom pulmonary cryptococcosis had been diagnosed to define the role of serum cryptococcal antigen (sCRAG) and radiographs during a follow-up period of up to 1 year.

DESIGN: Retrospective cohort study.

SETTING: University hospital.

PATIENTS: The clinical records, chest radiographs, and CT scan findings of 13 immunocompetent and 16 immunocompromised patients with a diagnosis based on cerebrospinal fluid (CSF) culture, sCRAG titers, and cytologic or histologic confirmation of the presence of pulmonary cryptococcosis were reviewed during the course of the study. Two thoracic radiologists reviewed chest radiographs and CT scans for morphologic characteristics and the distribution of parenchymal abnormalities, and a final reading was reached by consensus. The correlation between serial radiographs and sCRAG titers was examined in 9 immunocompetent and 10 immunocompromised patients.

MEASUREMENTS: Serum or CSF cryptococcal antigen.

RESULTS: The most common clinical symptom was cough, which was present in 24 patients (82.8%). Pulmonary nodules were the most frequent radiologic abnormality. Cavitation within nodules and parenchymal consolidation were significantly less common in immunocompetent patients compared to immunocompromised patients (p = 0.02 and p = 0.05, respectively). Immunocompromised patients tended to have a larger extent of pulmonary involvement than immunocompetent patients, the changes seen on their serial radiographs were more variable, and their corresponding sCRAG titers were higher (> 1:256). In the immunocompetent patients, the radiographic characteristics of lesions usually improved with a corresponding decrease in sCRAG titers over time.

CONCLUSIONS: Our study suggests that pulmonary cryptococcosis usually follows a benign clinical course in immunocompetent patients. Immunocompromised patients often undergo an evolution to cavitary lesions that represent a more aggressive disease nature. Serial radiographic changes and changes in sCRAG titers reliably reflect disease progression and the response to therapy.