Pulmonary cryptococcosis is a fungal infection caused by Cryptococcus gattii and C neoformans. The respiratory tract is the principal route of entry for infection via inhalation of fungal spores.
Cryptococcosis predominantly occurs in immunocompromised patients but can also be seen in immunocompetent hosts, particularly, those exposed to avian (e.g. pigeon) droppings. The spectrum of pulmonary cryptococcosis depends on the host's defenses.
The presentation of pulmonary cryptococcosis can range from asymptomatic nodular disease to severe acute respiratory distress syndrome (ARDS) 3:
- most often, causes several lung nodules or masses with or without cavitation, chiefly in immunocompromised patients
- additionally, consolidation, mediastinal lymphadenopathy, and pleural effusion may also be present.
In the immunocompetent host the pulmonary infections normally are asymptomatic, in contradistinction to the immunocompromised patient, in whom cryptococcal infection is most often symptomatic, and commonly disseminates to the central nervous system, skin, and bones 1.
Overall, approximately one third of patients are asymptomatic.
Symptoms range from a mild cough and low-grade fever to acute presentation with high fever and severe shortness of breath.
The method of entry is usually by inhalation of cryptococcal particles into the lungs, causing pulmonary infection. Spores are found worldwide in soil contaminated by avian droppings.
Serum cryptococcal antigen (sCRAG) levels are helpful in diagnosis and follow-up.
In general, there are several CT patterns that can be seen:
- clustered nodular pattern: most prevalent 4
- solitary pulmonary nodule or mass with or without cavitation
- scattered nodules
- peribronchovascular consolidation
The most common CT findings in immunocompetent patients with pulmonary cryptococcosis are pulmonary nodules. The nodules are most often multiple, smaller than 10 mm in diameter, and well-defined with smooth margins. The nodules usually involve less than 10% of the parenchyma and tend to be distributed peripherally in the middle and upper zones. Where there are multiple nodules, they are usually bilateral 2. Associated cavitation may be seen in up to 40% of cases 8. Occasionally, unusual presentation such as large cavities may be seen 13.
FDG PET-CT may play a complementary role to CT 6 and ~60% of patients show higher FDG uptake than the mediastinal blood pool 4.
Treatment and prognosis
- antifungals such as oral fluconazole or intravenous amphotericin B
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