Pleural fluid secondary to pulmonary cryptococcal infection: A case report and review of the literature

Background: Pulmonary Cryptococcosis (PC) is diagnosed with increasing incidence in recent years, but it does not commonly involve the pleural space. Here, we report a HIV-negative case with advanced stage IIIB non-small cell lung cancer (NSCLC) treated with radiation therapy presented with dyspnea, a new PET-positive lung mass and bilateral pleural effusion suspecting progressive cancer. However, the patient has been diagnosed as pulmonary cryptococcal infection and successfully treated with oral fluconazole therapy. Case presentation: A 77-year-old male with advanced stage non-small cell lung cancer treated with combined chemo-radiation therapy who presented with progressive dyspnea, a new PET-positive left lower lobe lung mass and bilateral pleural effusions. Initial diagnostic thoracentesis and bronchoscopy yielded no cancer, but instead found yeast forms consistent with cryptococcal organisms in the transbronchial biopsies of the left lower lobe lung mass. Subsequent to this, the previously collected pleural fluid culture showed growth of Cryptococcus neoformans. The same sample of pleural effusion was tested and was found to be positive for crytococcal antigen (CrAg) by a lateral flow assay (LFA). The patient has been treated with oral fluconazole therapy resulting in gradual resolution of the nodular infiltrates. Conclusion: PC should be considered in immunosuppressed cancer patients. Additionally, concomitant pleural involvement in pulmonary cryptococcal infections may occur. The incidence of false positive ¹⁸FDG-PET scans in granulomatous infections and the use of CrAg testing in pleural fluid to aid in diagnosis are reviewed.