Page 379 - Concise Pathology for Exam Preparation ( PDFDrive )

364 SECTION II Diseases of Organ Systems

Gross Morphology
• Overinflated lungs with small areas of atelectasis
• Occlusion of bronchi and bronchioles by thick tenacious mucous plugs
Microscopy
• Thickening of basement membrane of bronchial epithelium
• Oedema and inflammation in the bronchial walls (cells involved are eosinophils and
mast cells)
• Presence of Charcot–Leyden crystals (crystalloids made of eosinophil membrane
protein)
• Mucous plugs in bronchi and bronchioles containing whorls of shed epithelium
(Curschmann spirals)
• Increase in size of submucosal glands and hypertrophy of bronchial wall muscle
Clinical Features
• During an asthmatic episode the patient presents with chest tightness, dyspnoea,
wheezing and cough without production of sputum.
• Patient may be asymptomatic between asthmatic episodes.
• The most severe form of asthma is labelled ‘status asthmaticus’. This may last for days
to weeks, be unresponsive to treatment and lead to severe cyanosis and sometimes
death.

Bronchiectasis
Definition
Abnormal and permanent dilatation of proximal and medium-sized bronchi (. 2 mm in
diameter), caused by destruction of the muscular and elastic components of the bronchial
walls.
Causes
• Congenital bronchiectasis results from developmental arrest of the bronchial
tree, eg, bronchopulmonary sequestration, which is classified as either intralobar
or extralobar and results in chronic lower respiratory tact infections that later lead
to bronchiectasis.
• The more common acquired forms occur in adults and older children and require an
infectious insult, impairment of drainage, airway obstruction and/or a defect in host
defence. May be due to:
• Primary infections: Bronchiectasis may result as a consequence of necrotizing infec-
tions that are either poorly treated or not treated at all. Typical offending organisms
include Klebsiella species, Staphylococcus aureus, Mycobacterium tuberculosis, Myco-
plasma pneumoniae, Mycobacterium avium complex and certain viruses.
• Bronchial obstruction: Endobronchial tumours, foreign body impaction, right
middle lobe syndrome (results from an abnormal angulation of the lobar bronchus at
its origin, predisposing it to obstruction)
• Cystic fibrosis (CF): Bronchiectasis associated with CF is secondary to mucous
plugging of proximal airways and chronic pulmonary infection, especially with
P. aeruginosa.
• Young syndrome: This genetic variant of CF presenting with bronchiectasis, sinusitis
and azoospermia.
• Primary ciliary dyskinesia: It presents with immotile or dyskinetic cilia and/or
sperms. This may lead to poor mucociliary clearance, recurrent pulmonary infections
and ultimately, bronchiectasis. A variant of this condition, initially described by
Kartagener, comprises the clinical triad of situs inversus, nasal polyps, sinusitis and
bronchiectasis due to immotile cilia of the respiratory tract.
Gross Morphology
• Bronchiectasis may present as: (1) a focal process involving a lobe or a segment of the
lung or (2) a diffuse process involving both lungs. The former is the most common

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