B. Chronic Bronchitis.
C. Bronchial Asthma.
Image shows:honey-combed appearance of the lung.
- Bronchiectasis is defined as abnormal and irreversible dilatation of the bronchi and bronchioles (greater than 2 mm in diameter) developing secondary to inflammatory weakening of the bronchial walls.
- The most characteristic clinical manifestation of bronchiectasis is persistent cough with expectoration of copious amounts of foul-smelling, purulent sputum.
- The disease characteristically affects distal bronchi and bronchioles beyond the segmental bronchi.
- Grossly, the lungs may be involved diffusely or segmentally. Bilateral involvement of lower lobes occurs most frequently.
- More vertical air passages of left lower lobe are more often involved than the right.
- The pleura is usually fibrotic and thickened with adhesions to the chest wall.
- The dilated airways, depending upon their gross or bronchographic appearance, have been subclassified into the following different types :
- Cylindrical: the most common type characterised by tube-like bronchial dilatation.
- Fusiform: having spindle-shaped bronchial dilatation.
- Saccular: having rounded sac-like bronchial distension.
- Varicose: having irregular bronchial enlargements.
- Cut surface of the affected lobes, generally the lower zones, shows characteristic honey-combed appearance.
- The bronchi are extensively dilated nearly to the pleura, their walls are thickened and the lumina are filled with mucus or muco-pus. The intervening lung parenchyma is reduced and fibrotic.
Microscopically, fully-developed cases show the following histologic features :
- The bronchial epithelium may be normal, ulcerated or may show squamous metaplasia.
- The bronchial wall shows infiltration by acute and chronic inflammatory cells and destruction of normal muscle and elastic tissue with replacement by fibrosis.
- The intervening lung parenchyma shows fibrosis,while the surrounding lung tissue shows changes of interstitial pneumonia.
- The pleura in the affected area is adherent and shows bands of fibrous tissue between the bronchus and the pleura.