Aspergillus spores are widely disseminated in nature.
Inhalation leads to disease.
Organisms will proliferate in a pre-existing cavity in a immunocompetent host. Patients who have bronchiectasis secondary to obstruction, cystic fibrosis, sequestration etc. Patients who have tuberculosis. Patients who have abscesses. Patients with invasive aspergillus will have multiple, hemorrhagic, firm nodules which may be centered around blood vessels.