Obstructive Lung Disease D'W'Gutkin, M'D', Ph'D'

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Obstructive Lung DiseaseD.W.Gutkin, M.D., Ph.D.
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Obstructive Lung Disease

• 1. COPD (Chronic bronchitis, Emphysema)
• Bronchial Asthma
• Bronchiectasis
• Bronchiolitis
• Characterized by increased pulmonary resistance
  and limitation of expiratory flow rates

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Obstruction to Air Flow Can Be Due To

• 1. Airway narrowing - epithelial
  hyperplasia, hypersecretion of mucus with
  mucus plugs, scarring of airways, extrinsic
  compression.
• 2. Loss of elastic recoil - emphysema.

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COPD

• Chronic bronchitis and emphysema are two
  integrated processes, in which some individuals
  have more signs of bronchitis, others of
  emphysema - all are part of a spectrum of
  airway/lung injury.

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Chronic Bronchitis

• Clinical definition persistent cough with
  sputum production for at least 3 months in at
  least two consecutive years.
• Caused by chronic irritation of the airways by
  inhaled substances and/ or microbial infection -
  results in hypersecretion of mucus.

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Chronic Bronchitis Histology

• 1. Goblet cell hyperplasia and metaplasia.
• 2. Squamous metaplasia.
• 3. Submucosal gland hypertrophy and
  hyperplasia
• 4. Chronic inflammation.
• 5. Fibrosis.
• Reid index ratio of mucus glands to thickness
  of bronchial wall gt0.3 suggests CB.

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Emphysema

• Abnormal enlargement of air spaces distal to
  the terminal bronchiole accompanied by
  destruction of the walls of alveoli.
• Types (1) centrilobular (centriacinar)
• (2) panlobular (panacinar) (3) paraseptal
  (4) irregular

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Emphysema-Mechanisms

• Protease - antiprotease mechanism involves
  activation of elastases/proteases (e.g. by
  smoking)
• or
• Deficiencies in anti-protease mechanisms
  (alpha-1-antitrypsin), resulting in dissolution
  of lung substance - mediated by neutrophils and
  macrophages.

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Centrilobular Emphysema
From Robbins Pathologic Basis of Disease
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Panacinar Emphysema
From Robbins Pathologic Basis of Disease
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Emphysema

• Centrilobular central part of acinus (the
  respiratory bronchiole) is affected, distal acini
  are spared occurs in upper lobes smokers and
  coal workers.
• 2. Panlobular acini uniformly enlarged from
  level of RB to alveoli occurs in lower lobes
  alpha-1-antitrypsin deficiency .
• 3. Paraseptal distal acinus is affected
  especially seen adjacent to pleura, scars,
  interlobular septa responsible for spontaneous
  pneumothorax.
• 4. Irregular associated w/scarring
  unpredictable acinar involvement.

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Asthma

• Increased reactivity of the tracheobronchial
  tree to various stimuli, which illicit paroxysmal
  constriction of the smooth muscle of the
  bronchial airways.

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Asthma

• Immune reaction mediated by both IgE receptors
  on mast cells and basophils, and T cells that
  results in liberation of vasoactive and
  myospastic mediators.

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Asthma

• 1. Etiologies allergic, atopic, cold, exercise,
  drug-induced.
• 2. Signs wheeze, mucus plugs, air trapping.
• 3. CxR/ CT hyperexpansion of lungs focal
  atelectasis.

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Asthma - Histology

• 1. Goblet cell metaplasia and epithelial
  hyperplasia.
• 2. Thickened basement membrane of epithelium.
• 3. Submucosal eosinophils, lymphocytes,
  neutrophils.
• 4. Muscular hyperplasia/ hypertrophy.
• 5. Tracheobronchial glandular hypertrophy and
  hyperplasia.

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Bronchiectasis

• Chronic inflammatory condition involving the
  airways which results in permanent abnormal
  dilation - manifested clinically in the
  production of copious amounts of foul sputum.

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Bronchiectasis - Etiology

• 1. Post - inflammatory.
• 2. Congenital/ hereditary cystic fibrosis,
  ciliary disease, immune deficiency states.
• 3. Secondary to obstruction - foreign body,
  tumor.

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Bronchiectasis - Morphology

• Gross
• Large ectatic worm-like convoluted airways -
  saccular distension, fusiform distension,
  cylindrical ectasia.
• Microscopic
• Squamous metaplasia, acute and chronic
  inflammation, fibrosis of submucosa.

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Bronchiolitis

• Small airway inflammatory process, which may be
  associated with airflow obstruction
• Often accompanies chronic bronchitis, emphysema
  and bronchiectasis, but may occur as an
  independent entity.

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Bronchiolitis - Etiology

• connective tissue disorders
• infections
• inhalation of toxic substances
• organ transplantation

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Bronchiolitis - Histology

• Chronic inflammation of bronchial mucosa
• 2. Fibroblast proliferation and edema in the
  bronchiolar submucosa, compressing the small
  airways.