Cryptococcus neoformans is an encapsulated yeast found in pigeon and other bird droppings and can be inhaled by humans. The yeast grows within the alveoli, sometimes resulting in an encapsulated mass that is then resistant to neutrophil phagocytosis. Since cell-mediated immunity plays an important role in fighting the infection, most clinically apparent cases are diagnosed in immunosuppressed patients with HIV, transplant patients, or those receiving corticosteroids. Despite the lung being the portal of entry, cryptococcal infection usually affects the CNS and symptomatic pulmonary infection is uncommon. Diagnosis is made by identifying the antigen in fluid or by tissue identification because normal subjects can grow the organism in sputum samples. For this reason, flexible bronchoscopy with transbronchial biopsy, transthoracic needle aspiration, or open-lung biopsy is often necessary to definitively make the diagnosis. Dissemination can then be assessed by analyzing spinal fluid, urine, and blood samples. Sites of hematogenous dissemination include the cerebrospinal fluid, skin, bones, joints, kidneys, spleen, and prostate, and is more commonly seen in immunosuppressed patients. Dissemination is likely if serum cryptococcal antigen is positive.