Figure 1a. Pulmonary aspergillosis following hematopoietic stem cell transplantation. (a, b) CT scans obtained in two different patients show solitary nodules, with the nodule in b demonstrating cavitation. (c) CT scan obtained in a third patient shows multiple nodules surrounded by a halo of ground-glass attenuation, a finding that indicates hemorrhage resulting from pulmonary infarction. (d) CT scan obtained in a fourth patient shows tracheobronchial aspergillosis with debris filling the left lower lobe bronchus (arrowheads) and consolidation in the left lower lobe.