Fig. 24.1 Allergic bronchopulmonary aspergillosis in a 56-year-old asthmatic woman. (a) Mediastinal window image of CT scan (2.5-mm section thickness) obtained at level of right middle lobar bronchus shows allergic mucin (arrows) exhibiting high-attenuation tubular

lesions and filling lingular divisional bronchus and its branches. (b) Lung window image obtained at same level to (a) demonstrates mosaic perfusion area (open arrows) as well as allergic mucin (arrows)

Fig. 24.2 Status asthmaticus in a 45-year-old man. (a, b) Lung window images of thin-section (1.5-mm section thickness) CT scans obtained at levels of segmental bronchi (a) and subsegmental bronchi (b), respectively, show areas of mosaic perfusion (open arrows),

emphysema (curved arrows), and tree-in-bud signs (arrowheads). Also note marked bronchial wall thickening (arrows) and dilatation (small arrows) in both lungs

Asthma

Pathology and Pathogenesis

The airway lumen is compromised of the accumulation of mucus and an exudate of eosinophils and desquamated epithelial cells mixed with components derived from the plasma but not including fibrin. Three major processes appear to contribute to the airway narrowing: increased amounts of mucus, inflammatory edema, and muscular hypertrophy. These are found principally in bronchi but may also be found in smaller airways, including bronchioles. The inflammation may even involve alveoli. The mucus commonly has a

concentric or spiral pattern in cross section with many eosinophils and desquamated epithelium. There is goblet cell hyperplasia in the surface epithelium and the bronchial glands are enlarged, but not as much as in chronic bronchitis. The bronchioles may also contain mucous plugs and mucus may even be seen in alveolar ducts [4].

Symptoms and Signs

Patients typically present with symptoms such as episodic breathlessness, wheezing, chest tightness, and cough. Unlike COPD, asthma is episodic and reversible from the standpoint