Atypical bronchiolar and alveolar epithelial cells (AECs) were seen in all five patients, although the distribution was focal ( Figure 1J ). These atypical forms included multinucleated giant cells with irregularly distributed nuclei ( Figure 1K , L) or bronchiolar and AECs with large atypical nuclei, prominent eosinophilic nucleoli, and granular amphophilic cytoplasm ( Figure 1M ). However, distinct viral inclusions were not apparent.