Citation, DOI & article data
There are a number of recognized pulmonary forms, the number depending on the author 1,3,4 . Each form has specific clinical and radiological features and is discussed in separate articles:
- aspergilloma (saprophytic/noninvasive aspergillosis): the most common form seen radiographically
- allergic bronchopulmonary aspergillosis (ABPA)
- invasive aspergillosis
- obstructive bronchopulmonary aspergillosis
Other described groupings include 6:
- chronic pulmonary aspergillosis
The remainder of this article discusses general concepts pertaining to pulmonary aspergillosis.
The various species of Aspergillus are ubiquitous in the environment, and usually do not cause any human pathology, provided the lungs are structurally normal and the host immunity is intact. If either of these is abnormal, then there is the possibility that this otherwise benign fungus may cause pathology.
Role of immunity in aspergillosis
In a patient with normal immunity, Aspergillus is unable to cause pulmonary pathology. Altered immunity, both heightened (hypersensitivity) or reduced (immunocompromised) predisposes to Aspergillus-related lung disease.
Patients with hypersensitivity may develop allergic bronchopulmonary aspergillosis (ABPA), whereas immunocompromised patients can develop semi-invasive or invasive aspergillosis depending on the degree to which their immune system is depressed.
Role of pulmonary structure in aspergillosis
Aspergillus can colonize pre-existing pulmonary cavities, particularly those left behind by pulmonary tuberculosis. In this setting, the fungus grows and, as it is free to move within the cavity, typically takes on a spherical shape, and is known as an aspergilloma. Other cavities that can predispose to aspergilloma include bullae which may be secondary to emphysema.
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