PMNs suggest infection. Progressive disease is the exception. Asthma is increasing in many countries. However, even in patients dying of asthma, airways are not uniformly involved, although bronchi are more uniformly involved than bronchioles. Bronchial arteries and veins are increased in number.
Epithelium is hyperplastic with goblet cell or squamous metaplasia.
Eosinophils and mast cells also infiltrate the epithelial layer. Groups of sloughed epithelial cells round up to form Creola bodies, which can be seen in the sputum. They are distinguished from adenocarcinoma by their small nucleoli and the presence of cilia. In contrast to other inflammatory conditions in the lung, inflammation tends to persist, but dense scar is unusual. Asthma, a syndrome with many different causes and pathogenetic mechanisms, has at its basis airway hyperresponsiveness.