The tumor was poorly preserved in sections taken postmortem, but diagnostic features were still present. In the following two photos, tumor cells line alveolar walls as a single layer of cells. A single layer of columnar cells lines some alveolar walls, but others are not involved and appear normal. The alveoli, however, are distended with mucus. Contiguous alveoli are lined by columnar cells with basal nuclei.
Mucinous secretion is present in the airway at the bottom.