Page 500 - Textbook of Pathology, 6th Edition

484 neutrophils. These result in further release of mediators oedema and inflammatory infiltrate consisting of
which accentuate the above-mentioned effects. In addition, lymphocytes and plasma cells with prominence of eosino-
inflammatory injury is caused by neutrophils and by major phils. There is hypertrophy of submucosal glands as well
basic protein (MBP) of eosinophils. as of the bronchial smooth muscle.
2. Intrinsic (idiosyncratic, non-atopic) asthma. This type 4. Changes of bronchitis and emphysema may super-
of asthma develops later in adult life with negative personal vene, especially in intrinsic asthma.
or family history of allergy, negative skin test and normal
serum levels of IgE. Most of these patients develop typical CLINICAL FEATURES. Asthmatic patients suffer from
symptom-complex after an upper respiratory tract infection episodes of acute exacerbations interspersed with symptom-
by viruses. Associated nasal polypi and chronic bronchitis free periods. Characteristic clinical features are paroxysms
are commonly present. There are no recognisable allergens of dyspnoea, cough and wheezing. Most attacks typically
but about 10% of patients become hypersensitive to drugs, last for a few minutes to hours. When attacks occur
most notably to small doses of aspirin (aspirin-sensitive continuously it may result in more serious condition called
asthma). status asthmaticus. The clinical diagnosis is supported by
demonstration of circulation eosinophilia and sputum
3. Mixed type. Many patients do not clearly fit into either
of the above two categories and have mixed features of both. demonstration of Curschmann’s spirals and Charcot-Leyden
Those patients who develop asthma in early life have strong crystals. More chronic cases may develop cor pulmonale.
allergic component, while those who develop the disease late
tend to be non-allergic. Either type of asthma can be BRONCHIECTASIS
precipitated by cold, exercise and emotional stress. Bronchiectasis is defined as abnormal and irreversible
dilatation of the bronchi and bronchioles (greater than 2 mm
MORPHOLOGIC FEATURES. The pathologic changes in diameter) developing secondary to inflammatory
are similar in both major types of asthma. The pathologic weakening of the bronchial walls. The most characteristic
material examined is generally autopsy of lungs in clinical manifestation of bronchiectasis is persistent cough
patients dying of status asthmaticus but the changes are with expectoration of copious amounts of foul-smelling,
expected to be similar in non-fatal cases. purulent sputum. Post-infectious cases commonly develop
Grossly, the lungs are overdistended due to over-inflation. in childhood and in early adult life.
The cut surface shows characteristic occlusion of the ETIOPATHOGENESIS. The origin of inflammatory destruc-
bronchi and bronchioles by viscid mucus plugs. tive process of bronchial walls is nearly always a result of
SECTION III
Microscopically, the following changes are observed two basic mechanisms: endobronchial obstruction and
(Fig. 17.21): infection.
1. The mucus plugs contain normal or degenerated Endobronchial obstruction by foreign body, neoplastic
respiratory epithelium forming twisted strips called growth or enlarged lymph nodes causes resorption of air
Curschmann’s spirals. distal to the obstruction with consequent atelectasis and
2. The sputum usually contains numerous eosinophils retention of secretions.
and diamond-shaped crystals derived from eosinophils Infection may be secondary to local obstruction and
called Charcot-Leyden crystals. impaired systemic defense mechanism promoting bacterial
3. The bronchial wall shows thickened basement growth, or infection may be a primary event i.e.
membrane of the bronchial epithelium, submucosal
bronchiectasis developing in suppurative necrotising
Systemic Pathology
pneumonia.
These 2 mechanisms—endobronchial obstruction and
infection, are seen in a number of clinical settings as under:
1. Hereditary and congenital factors. Several hereditary
and congenital factors may result secondarily in diffuse
bronchiectasis:
i) Congenital bronchiectasis caused by developmental defect
of the bronchial system.
ii) Cystic fibrosis, a generalised defect of exocrine gland
secretions, results in obstruction, infection and bronchiectasis
(Chapter 22).
iii) Hereditary immune deficiency diseases are often associated
with high incidence of bronchiectasis.
iv) Immotile cilia syndrome that includes Kartagener’s
syndrome (bronchiectasis, situs inversus and sinusitis) is
characterised by ultrastructural changes in the microtubules
causing immotility of cilia of the respiratory tract epithelium,
Figure 17.21 Diagrammatic appearance of Curschmann’s spiral and
Charcot-Leyden crystals found in mucus plugs in patients with bronchial sperms and other cells. Males in this syndrome are often
asthma. infertile (Chapter 23).