Obstructive Lung Diseases

Slide 1 · Obstructive lung diseases

Mechanisms, morphology, and clinicopathologic patterns

COPD · Asthma · Bronchiectasis

Dr Abu Suraih Sakhri

MBBS, MD (Pathology)

www.abusuraihsakhri.com

Slide 2 · Teaching objectives

Define the mechanism of airflow obstruction and its spirometric pattern

Localize the major obstructive disorders to bronchi, bronchioles, or acini

Link characteristic morphology to symptoms and functional impairment

Distinguish COPD, asthma, and bronchiectasis using pathology

Slide 3 · Airflow obstruction: The central lesion

Diffuse airway disease increases resistance to moving air

Obstruction can occur at several levels of the respiratory tree

Forced expiration is particularly affected

Diffuse airway disease

Increased resistance

Reduced expiratory airflow

Schematic

Slide 4 · Obstructive versus restrictive physiology

OBSTRUCTIVE

RESTRICTIVE

Increased airway resistance

Reduced maximal forced expiratory flow

Low FEV₁/FVC ratio

Reduced lung expansion and total lung capacity

FEV₁ decreases proportionately with FVC

FEV₁/FVC ratio remains normal

Slide 5 · FEV₁/FVC: Physiological distinction

FEV₁ quantifies volume expired during the first second of forced exhalation

FVC is the total volume expired during forced expiration

FEV₁/FVC below 0.7 generally indicates obstruction

Restriction produces proportionate reductions, preserving the ratio

FEV₁ / FVC

< 0.7: Usually obstruction

Slide 6 · Why forced expiration is affected

Narrowing of airway caliber increases resistance

Loss of surrounding elastic support allows small airways to collapse

Mucus plugs and airway-wall inflammation further restrict expiration

Narrowed / unsupported lumen

Airflow resistance ↑

Expiratory flow ↓

Schematic

Slide 7 · Anatomic sites of airway disease

Bronchus

Bronchitis · asthma · bronchiectasis

Bronchiole

Small-airways fibrosis

Acinus

Emphysema

Slide 8 · Five pathology patterns associated with obstruction

Disease

Primary site

Dominant change

Chronic bronchitis

Bronchus

Mucous gland enlargement

Bronchiectasis

Bronchus

Dilation and scarring

Asthma

Bronchus

Smooth muscle, mucus, inflammation

Emphysema

Acinus

Wall destruction

Small-airways disease

Bronchiole

Inflammatory scarring

Slide 9 · A single functional defect, distinct substrates

LUMINAL NARROWING

LOSS OF TETHERING

Mucus accumulation reduces the conducting lumen

Bronchospasm transiently narrows bronchial caliber

Alveolar destruction reduces elastic traction

Small airways collapse preferentially during expiration

Slide 10 · Obstructive disorders frequently coexist

COPD

Emphysema + bronchitis

Asthma

Variable bronchospasm

Overlapping airflow physiology

Schematic

Slide 11 · Shared exposures, different lesions

Cigarette smoke is a major shared cause of emphysema and bronchitis

Air pollutants contribute to chronic airway inflammation

Infections exacerbate established COPD and can injure bronchi in bronchiectasis

Inhaled injury

Airway / acinar damage

Overlapping phenotypes

Schematic

Slide 12 · COPD: Clinicopathologic definition

Persistent respiratory symptoms accompany airflow limitation

Abnormalities may involve airways, alveoli, or both

Exposure to noxious particles or gases is central to the textbook definition

Slide 13 · COPD contains two major injury patterns

EMPHYSEMA

CHRONIC BRONCHITIS

Alveolar wall destruction

Loss of elastic recoil

Dynamic expiratory collapse

Mucus hypersecretion

Inflamed and scarred bronchioles

Airway plugging

Slide 14 · Risk factors for COPD

Heavy cigarette smoking has a strong association with COPD

Environmental and occupational pollutant exposure contributes

Poor early-life lung development and airway hyperresponsiveness contribute

Certain genetic polymorphisms modify risk

Slide 15 · COPD: Pathways to airflow limitation

Small-airway inflammation and fibrosis narrow bronchioles

Bronchitic mucus hypersecretion obstructs lumens

Emphysema reduces radial traction and expiratory patency

Small-airways disease

Mucus / wall injury

Loss of recoil

Schematic

Slide 16 · Emphysema is a destructive acinar disease

Airspaces distal to terminal bronchioles enlarge irreversibly

Destruction of alveolar walls is essential to the definition

Expansion without destruction is not equivalent to true emphysema

Respiratory bronchiole

Alveolar duct / alveoli

Schematic · distribution only, not histology

Slide 17 · Acinar anatomy determines emphysema type

The acinus is the terminal respiratory unit beyond a terminal bronchiole

Respiratory bronchioles form proximal acinar components

Alveolar ducts and alveoli occupy more distal portions

Respiratory bronchiole

Alveolar duct / alveoli

Schematic · distribution only, not histology

Slide 18 · Emphysema classification by distribution

Type

Acinar zone

Principal association

Centriacinar

Proximal acinus

Smoking; Upper lobes

Panacinar

Entire acinus

α₁-antitrypsin deficiency

Distal acinar

Peripheral acinus

Subpleural blebs

Irregular

Patchy

Scarring

Slide 19 · Centriacinar emphysema

Respiratory bronchioles are affected before distal alveoli

Emphysematous and relatively preserved spaces coexist in one acinus

Upper lobes, particularly apices, are often more severely affected

Closely associated with heavy cigarette smoking

Respiratory bronchiole

Alveolar duct / alveoli

Schematic · distribution only, not histology

Slide 20 · Panacinar emphysema

The acinus enlarges from respiratory bronchiole to terminal alveoli

Often involves lower lung zones and is most severe at lung bases

Associated with α₁-antitrypsin deficiency; Smoking worsens disease

Respiratory bronchiole

Alveolar duct / alveoli

Schematic · distribution only, not histology

Slide 21 · Centriacinar versus panacinar patterns

CENTRIACINAR

PANACINAR

Proximal acinar injury

Initially spared distal airspaces

Smoking-associated; Often upper-lobe dominant

Uniform acinar involvement

Respiratory bronchioles to terminal alveoli

α₁-antitrypsin deficiency; Lower-zone bias

Slide 22 · Distal acinar and irregular emphysema

PARASEPTAL

IRREGULAR

Peripheral acinar destruction

Subpleural involvement

May be associated with spontaneous pneumothorax

Nonuniform, scar-associated lesions

Often limited focal involvement

Frequently of little functional significance

Slide 23 · Tobacco smoke drives acinar injury

Inhaled toxic particles damage respiratory epithelium

Resident cells and inflammatory cells amplify local inflammation

Inflammatory mediators promote leukocyte influx and matrix injury

Tobacco smoke

Epithelial injury

Inflammatory recruitment

Matrix destruction

Schematic

Slide 24 · Protease–antiprotease imbalance

Neutrophils and other cells release proteolytic enzymes

Antiproteases normally restrain destruction of matrix proteins

Relative antiprotease deficiency favors alveolar wall breakdown

Proteases ↑

Antiprotease defense ↓

Elastic matrix loss

Schematic

Slide 25 · α₁-Antitrypsin protects alveolar matrix

α₁-Antitrypsin inhibits proteases, notably neutrophil elastase

Severe deficiency increases susceptibility to emphysema

Panacinar change is especially associated with deficiency

Smoking amplifies inflammatory protease burden

α₁-antitrypsin ↓

Elastase activity unopposed

Parenchymal loss

Schematic

Slide 26 · Oxidant-mediated parenchymal injury

Oxidants originate from cigarette smoke and inflammatory cells

Oxidative stress produces tissue damage and sustains inflammation

NRF2 activates cellular defenses against oxidant injury

Oxidants ↑

Protective response insufficient

Alveolar injury

Schematic

Slide 27 · How alveolar destruction obstructs airflow

Intact parenchyma provides radial traction on respiratory bronchioles

Destruction reduces elastic recoil and the outward tethering force

Small airways collapse during expiration despite no fixed intraluminal plug

Alveolar wall loss

Radial traction ↓

Expiratory collapse

Schematic

Slide 28 · Loss of recoil versus fixed narrowing

DYNAMIC COLLAPSE

FIXED NARROWING

Emphysema removes alveolar elastic tissue

Radial traction falls

Bronchioles collapse during expiration

Bronchiolitis causes inflammation and fibrosis

Wall changes narrow the lumen

Both mechanisms may coexist in COPD

Slide 29 · Gross emphysema: Characteristic architecture

Advanced lungs are voluminous and hyperinflated

The anterior lung may overlap the heart; Diaphragm becomes flattened

Cut sections contain visibly enlarged airspaces and sometimes bullae

Slide 30 · Microscopic emphysema: What is lost?

Enlarged airspaces have attenuated or destroyed septa

Small-airway attachments and the capillary bed are reduced

Thin residual septa may form projecting or blind-ended strands

Enlarged airspaces

Schematic, not a photomicrograph

Slide 31 · Capillary loss compounds emphysema

Alveolar destruction removes gas-exchanging surface area

Capillary bed reduction accompanies septal destruction

Hypoxemia and vascular injury can contribute to pulmonary hypertension

Alveolar septa lost

Capillary surface ↓

Gas exchange impaired

Schematic

Slide 32 · Bullae and pneumothorax

Blebs and bullae may complicate advanced emphysema

Subpleural airspaces can rupture

Air entering the pleural cavity produces pneumothorax

Subpleural bulla

Rupture

Pneumothorax

Schematic

Slide 33 · Chronic bronchitis is clinically defined

Productive cough for at least 3 months per year

Present over at least 2 consecutive years

No other identifiable explanation for the cough and sputum

The clinical definition is distinct from histologic gland enlargement

Slide 34 · Chronic bronchitis: Epithelial response

Smoke and other irritants injure airway-lining cells

Mucus glands enlarge within larger conducting airways

Goblet cells also increase within smaller bronchi and bronchioles

Airway cross-section · schematic

Slide 35 · Mucous gland enlargement explains sputum

Submucosal glands enlarge in trachea and bronchi

Increased secretory capacity raises mucus burden

Excess mucus forms a physical obstacle within airway lumens

Gland hyperplasia

Mucus secretion ↑

Airway plugging

Schematic

Slide 36 · Acquired CFTR dysfunction in smokers

The text identifies smoking-related acquired CFTR dysfunction

Altered secretion contributes to dehydrated, abnormal mucus

Thick secretions aggravate chronic bronchitic symptoms

Cigarette smoke

Acquired CFTR dysfunction

Dehydrated mucus

Schematic

Slide 37 · Impaired ciliary clearance favors infection

Cigarette smoke interferes with ciliary function

Retained mucus favors microbial persistence

Infections may sustain bronchitis and precipitate exacerbations

Ciliary impairment

Secretion retention

Infective exacerbation

Schematic

Slide 38 · Chronic inflammation scars small airways

Irritant injury recruits neutrophils, macrophages, and lymphocytes

Wall thickening reflects inflammatory injury and matrix deposition

Peribronchiolar fibrosis narrows the small-airway lumen

Chronic inflammation

Airway wall fibrosis

Luminal narrowing

Schematic

Slide 39 · The Reid index and bronchial gland thickening

Reid index compares gland-layer thickness with bronchial wall thickness

A normal value around 0.4

The index typically rises with chronic bronchitis

Its measurement describes morphology, not the clinical cough definition

Mucosa

Submucosal glands

Cartilage

Reid index = gland thickness / wall thickness

Schematic; Relative dimensions not measured

Slide 40 · Microscopic airway remodeling in bronchitis

Goblet cell hyperplasia accompanies mucus-gland enlargement

Smooth muscle thickening and peribronchial fibrosis may occur

Some small airways are severely narrowed or obliterated

Squamous metaplasia or dysplasia may accompany smoke exposure

Airway cross-section · schematic

Slide 41 · COPD presentation reflects mixed pathology

Slowly progressive exertional dyspnea and chronic cough are frequent

Sputum burden increases with a bronchitic contribution

Acute infections can precipitate symptomatic exacerbations

Spirometry is central to recognizing airflow limitation

Slide 42 · Predominantly emphysematous COPD

EMPHYSEMA-DOMINANT

BRONCHITIS-DOMINANT

Dyspnea and hyperinflation predominate

Cough may be slight

Diffusing capacity can be low

Chronic productive cough predominates

Airway resistance is increased

Hypoxemia and hypercapnia may occur

Slide 43 · Predominantly bronchitic COPD

Productive cough is the dominant clinical feature

Hypoxemia and hypercapnia can become marked

Pulmonary hypertension and cor pulmonale may develop

Most patients have mixed emphysematous and bronchitic findings

Slide 44 · Pulmonary hypertension in advanced COPD

Persistent hypoxemia contributes to vascular changes

Loss of capillary beds accompanies alveolar destruction

Pulmonary hypertension increases right ventricular afterload

Cor pulmonale may follow advanced disease

Lung injury / hypoxemia

Pulmonary hypertension

Right-heart strain

Schematic

Slide 45 · Asthma: Variable expiratory obstruction

Chronic airway inflammation underlies heterogeneous phenotypes

Episodic wheeze, dyspnea, cough, and chest tightness fluctuate

Bronchoconstriction is central to acute attacks

Between attacks some patients are nearly asymptomatic

Slide 46 · Asthma: Three contributors to narrowing

Contraction of airway smooth muscle produces bronchospasm

Mucosal edema and excess mucus further reduce lumen diameter

Chronic remodeling may add persistent airflow limitation

Airway cross-section · schematic

Slide 47 · Common asthma triggers

Environmental allergens can provoke atopic disease

Respiratory infections and inhaled irritants exacerbate attacks

Cold air, exercise, and stress may also precipitate symptoms

Trigger exposure

Airway hyperresponsiveness

Bronchospasm

Schematic

Slide 48 · Atopic asthma: Allergen sensitization

The textbook frames atopic disease as type I hypersensitivity

Th2 polarization and IgE sensitization precede responses to allergens

Allergic rhinitis, eczema, and family history may coexist

Environmental allergen

Th2 response / IgE

Mast-cell activation

Schematic

Slide 49 · Nonatopic asthma: No allergen sensitization

Skin tests for allergen sensitization are generally negative

Viral infection is an important trigger

Irritants and physical triggers contribute to airway hyperreactivity

Slide 50 · Aspirin-sensitive asthma

Associated with recurrent rhinitis and nasal polyps

Aspirin and some other nonsteroidal anti-inflammatory drugs trigger attacks

Cyclooxygenase inhibition shifts mediator balance toward leukotriene effects

COX pathway inhibited

Prostaglandin E₂ ↓

Leukotriene-mediated response

Schematic

Slide 51 · Occupational asthma

Fumes, chemical dusts, gases, and other agents can trigger attacks

Attacks generally follow repeated occupational exposure

Mechanisms differ: IgE responses or other bronchoconstrictor pathways

Slide 52 · Th2 cytokines in atopic asthma

Mediator

Principal effect

Pathology consequence

IL-4

B-cell IgE production

Allergen sensitization

IL-5

Eosinophil activation

Eosinophilic inflammation

IL-13

Mucus production

Secretory hyperplasia

Slide 53 · Immediate allergic response in asthma

Allergen exposure activates mast cells bearing surface IgE

Bronchoconstriction dominates the early reaction

Mucus secretion, vasodilation, and permeability also increase

IgE-bound mast cell

Mediator release

Bronchospasm + mucus

Schematic

Slide 54 · Late-phase inflammatory reaction

Recruitment of eosinophils and additional leukocytes follows

T cells and epithelial chemokines sustain the response

Repeated injury lays the foundation for airway remodeling

Leukocyte recruitment

Inflammatory persistence

Remodeling

Schematic

Slide 55 · Type 2 immunity extends beyond Th2 cells

Type 2 innate lymphoid cells can produce similar cytokines

Epithelial injury releases signals capable of activating ILC2s

Type 2 inflammation is not exclusively antigen-receptor dependent

Epithelial injury

ILC2 activation

Type 2 cytokines

Schematic

Slide 56 · Asthma remodeling creates a fixed component

Smooth muscle hypertrophy and hyperplasia thicken the airway wall

Subepithelial fibrosis stiffens bronchial architecture

Mucous gland and goblet cell increases enlarge secretory burden

New vessels and chronic inflammatory cells further thicken the wall

Airway cross-section · schematic

Slide 57 · Morphology of acute severe asthma

Lungs may be hyperinflated with focal atelectasis

Bronchi and bronchioles can be blocked by tenacious mucus

Mucus plugs may contain desquamated respiratory epithelium

Airway cross-section · schematic

Slide 58 · Eosinophils and mucus-plug structures

Atopic asthma sputum may contain numerous eosinophils

Curschmann spirals represent coiled mucus material

Charcot–Leyden crystals contain eosinophil-derived galectin-10

Slide 59 · Asthma and COPD are not mutually exclusive

COPD

Emphysema + bronchitis

Asthma

Variable bronchospasm

Overlapping airflow physiology

Schematic

Slide 60 · Acute severe asthma: Functional risk

Unremitting bronchospasm may persist for days or weeks

Mucus obstruction and edema further restrict ventilation

Severe attacks can produce cyanosis and may be fatal

Severe bronchospasm

Mucus + edema

Critical airflow limitation

Schematic

Slide 61 · Bronchiectasis: Permanent bronchial dilation

Inflammation destroys bronchial smooth muscle and elastic tissue

Damaged airway walls become irreversibly dilated

Persistent or severe infection and defective clearance are central

Airway cross-section · schematic

Slide 62 · Bronchiectasis: Major predisposing settings

Setting

Initiating defect

Typical consequence

Cystic fibrosis

Viscous mucus

Often widespread

Primary ciliary dyskinesia

Defective ciliary clearance

Recurrent infections

Tumor / foreign body

Focal obstruction

Localized

Severe infection

Necrotizing airway injury

Bronchial wall destruction

Immune disturbance

Altered host defense

Chronic infection

Slide 63 · Obstruction–infection cycle

Impaired clearance

Persistent infection

Inflammatory wall injury

Bronchial dilation

Self-perpetuating injury

Schematic

Slide 64 · Cystic fibrosis and bronchiectasis

Abnormal ion transport generates viscous mucus

Defective mucociliary clearance promotes airway obstruction

Recurrent infections damage airway walls

Bronchi dilate while small bronchioles may scar shut

Viscous mucus

Impaired clearance

Chronic infection

Airway destruction

Schematic

Slide 65 · Primary ciliary dyskinesia

Defects in ciliary motor proteins impair mucus clearance

Recurrent respiratory infection creates bronchiectatic injury

Kartagener syndrome links bronchiectasis, sinusitis, and situs inversus

Ciliary dysfunction

Recurrent infection

Bronchiectasis

Schematic

Slide 66 · Allergic bronchopulmonary aspergillosis

Occurs in some patients with asthma or cystic fibrosis

A hypersensitivity response to Aspergillus drives eosinophilic inflammation

Mucus plugging contributes to subsequent bronchial dilation

Aspergillus sensitization

Eosinophilic inflammation

Mucus plugging / damage

Schematic

Slide 67 · Bronchiectasis: Gross morphology

Bronchi and bronchioles are widened, sometimes markedly

Damaged peripheral conducting airways may extend near the pleura

Cyst-like dilated bronchi can contain mucopurulent material

Airway cross-section · schematic

Slide 68 · Bronchiectasis: Active microscopic injury

Acute and chronic inflammatory cells occupy damaged airway walls

Epithelial sloughing and ulceration may be prominent

Necrosis can progress to abscess formation

Slide 69 · Bronchiectasis: Chronic sequelae

Fibrosis and peribronchiolar scarring accompany chronic injury

Squamous metaplasia may further impair mucociliary clearance

Progressive fibrosis can markedly reduce bronchiolar lumens

Wall inflammation

Fibrosis + metaplasia

Airway dysfunction

Schematic

Slide 70 · A single comparison: Mechanism of obstruction

Entity

Dominant tissue change

Functional consequence

Chronic bronchitis

Mucous gland enlargement

Plugging / small-airway injury

Asthma

Bronchospasm; Inflammation

Variable airway narrowing

Emphysema

Alveolar wall destruction

Loss of radial traction

Bronchiectasis

Bronchial wall destruction

Dilation / secretion stasis

Slide 71 · Clinical clues to the anatomic lesion

Prominent dyspnea and hyperinflation suggest emphysema contribution

Chronic productive cough suggests bronchitic mucus hypersecretion

Episodic wheeze favors asthma physiology

Purulent sputum with recurrent infection supports bronchiectasis

Slide 72 · Case reasoning: Progressive dyspnea

A long-term smoker develops gradually worsening exertional dyspnea

The lungs show enlarged airspaces and reduced elastic tissue

What mechanism best explains expiratory airflow limitation?

Answer: Loss of radial traction promotes small-airway collapse

Slide 73 · Case reasoning: Recurrent purulent sputum

A patient has repeated infections and copious purulent sputum

Airways are permanently dilated and surrounded by fibrosis

What sequence connects the infection to the structural defect?

Answer: Persistent inflammation destroys smooth muscle and elastic tissue

Slide 74 · Case reasoning: Fluctuating wheeze

Episodes of wheeze follow allergen exposure

The airway shows mucus, eosinophils, and smooth-muscle thickening

Which pathways explain acute obstruction and chronic structural change?

Answer: Mast-cell bronchospasm plus type 2 inflammatory remodeling

Slide 75 · Synthesis: Trace morphology to physiology

Identify the anatomic compartment: Bronchus, bronchiole, or acinus

Identify the process: Mucus, smooth muscle, fibrosis, or matrix loss

Explain how the process decreases expiratory flow

Expect overlap rather than rigidly separated clinical categories

Anatomic site

Morphologic lesion

Airflow consequence

Schematic

Slide 76 · Reference and source boundaries

Robbins, Cotran & Kumar: Pathologic Basis of Disease, 11th edition (2026)

Chapter 15, The Lung — obstructive/restrictive framework and obstructive diseases

Source-grounded overview extended into adjacent COPD, asthma, and bronchiectasis sections

Conceptual drawings are original editable schematics; not specimens