Abstract

Cryptococcosis is a common opportunistic infection in acquired immunodeficiency syndrome (AIDS) patients, also occurring in other immunosuppressed patients and occasionally those with no apparent immunocompromise. The majority of cases are caused by the ubiquitous encapsulated yeast, Cryptococcus neoformans, whereas Cryptococcus GATTII accounts for a smaller proportion of cases, often in immunocompetent patients. Severe meningoencephalitis is the commonest presentation; however, pulmonary cryptococcosis in human immunodeficiency virus (HIV)-seropositive individuals is underdiagnosed and without appropriate treatment leads to severe disseminated disease. The natural history of pulmonary cryptococcal infection in other immunosuppressed patients is also of dissemination and progression in the majority of cases, whereas immunocompetent patients may present with more localized, self-limiting disease. The presentation is usually with nonspecific respiratory symptoms, although severe respiratory failure has been reported in both immunocompromised and immunocompetent patients. Radiological presentations are varied and nonspecific, influenced by the underlying immune status of the patient. Diagnosis is based on isolation of Cryptococcus from, or detection of cryptococcal antigen in, a pulmonary specimen, coupled with appropriate clinical, radiological, and histopathological findings. Antifungal treatment with amphotericin B +/- flucytosine is recommended for severe disease, whereas fluconazole is the treatment of choice for mild and localized infections.