B72-27 Cryptococcus Neoformans Pulmonary Nodule in an Immunocompetent Host

Abstract Introduction Cryptococcus neoformans is an opportunistic fungal pathogen that primarily affects immunocompromised individuals. However, pulmonary cryptococcosis can also occur in immunocompetent hosts, often presenting as an incidental lung nodule detected on imaging. Case Presentation A 79-year-old immunocompetent male with obstructive sleep apnea and mild centrilobular emphysema presented with dry cough and shortness of breath. He was found to have an incidental 3-mm right upper lobe lung nodule on a computed tomography (CT) in 2017. Surveillance imaging showed growth to 7 mm by 2018 and an increase to 10 × 6 mm by 2024 (Figure 1). Robotic-assisted bronchoscopy identified a 7-mm peripheral pulmonary nodule, but biopsy was nondiagnostic. Bronchoalveolar lavage fluid cultured Cryptococcus neoformans, though serum cryptococcal antigen was negative. Differential cell counts showed neutrophil predominance (42%) with low lymphocytes (8%) and macrophages (41%). Cytology was negative and no acid-fast bacilli were detected. The patient, a former smoker (20 pack-years, quit more than 20 years ago), denied alcohol use, travel, or bird exposure. Patient completed therapy with Fluconazole 400 mg daily and subsequent 200 mg daily dose which resulted in resolution of symptoms. Discussion Cryptococcus is a ubiquitous fungus found worldwide in soil, particularly in bird droppings. Transmission occurs via inhalation, allowing the yeast to remain dormant in the lungs. The infection can be caused by C.neoformans or C.gattii. While C.gattii infections are more common in immunocompetent individuals, C.neoformans typically affects immunocompromised hosts. However, our patient, despite lacking apparent immunosuppression, was infected with C.neoformans, similar to two reported cases of pulmonary cryptococcosis in immunocompetent individuals published in CHEST. A retrospective study of 68 patients with pulmonary cryptococcosis found that 57.35% had clinical symptoms, primarily cough, and 8.82% had a history of occupational exposure. CT findings in immunocompetent patients with pulmonary cryptococcosis typically reveal pulmonary nodules or masses with a predominantly peripheral distribution in 80% of cases. Most nodules are smaller than 10 millimeters, well-defined, smooth-margined, and located peripherally in the middle and upper lung zones. Pulmonary cryptococcosis can produce solitary lung lesions that may be surgically curable. If unresected, these lesions can lead to dissemination and fatal outcomes, as current medical treatment is not always reliable. In immunocompetent hosts with isolated pulmonary disease, careful observation may be warranted. However, in symptomatic cases, such as for our patient with dry cough and shortness of breath, the recommended treatment is fluconazole, 200 to 400 milligrams per day for three to six months. This abstract is funded by: None