Pulmonary cryptococcosis

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:

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.

Serology

Serum cryptococcal antigen (sCRAG) levels are helpful in diagnosis and follow-up.

CT

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.

Nuclear medicine

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.

  • antifungals such as oral fluconazole or intravenous amphotericin B
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Article Information

rID: 16417
System: Chest
Section: Pathology
Synonyms or Alternate Spellings:
  • Pulmonary cryptococcus infection
  • Lung involvement in cryptococcosis
  • Pulmonary involvement in cryptococcosis
  • Pulmonary cryptococcal infection
  • Pulmonary cryptococcal infections
  • Cryptococcal infection of the lung
  • Cryptococcal infection of the lungs

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Cases and Figures

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    Case 1: with cavitatory nodule
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    Case 2
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    Case 3: cryptococcal granuloma - right base
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    Case 4: biopsy proven
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    Case 5
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    Case 6
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