Slide A
Aspergillus species may infect abnormal airways (e.g. old tuberculous or bronchiectatic cavities) and remain non-invasive. In immunocompromised patients, however, this fungus may invade the lung parenchyma, causing a severe, often necrotizing, pneumonia. In this section taken from the lung of an organ transplant patient, the bronchial lumen is virtually filled by a mass of fungal hyphae.

Slide B
At higher power, note the hyphae invading the bronchial wall.