Lung - Robbins Basic Pathology - 2022 PDF

2022 Lung Robbins Basic Pathology Dr. P. Babaheidrian Associate professor of pathology, IUMS Right Left 2 3  The alveolar walls (or alveolar septa) consist of: The capillary endothelium and basement membrane...

2022 Lung Robbins Basic Pathology Dr. P. Babaheidrian Associate professor of pathology, IUMS Right Left 2 3  The alveolar walls (or alveolar septa) consist of: The capillary endothelium and basement membrane The pulmonary interstitium Alveolar epithelium
type I pneumocytes (95%)


type II pneumocytes (surfactant & repair)





alveolar macrophages

.
4 5 Lung diseases can broadly be divided into those affecting : (1) The airways (2) The interstitium (3) The pulmonary vascular system.
6  ATELECTASIS (COLLAPSE)

Is loss of lung volume caused by inadequate expansion of air spaces Resorption atelectasis Compression atelectasis Contraction atelectasis (or cicatrization atelectasis) 7 8 ARDS ARDS is a clinical syndrome of progressive respiratory insufficiency caused by diffuse alveolar damage (DAD) in the setting of sepsis, severe trauma, or diffuse pulmonary infection. Neutrophils are thought to have an important role in the pathogenesis of ARDS.
9  Pneumonia (35%–45%) The most frequent triggers Sepsis (30%–35%) Aspiration, trauma (including brain injury,
abdominal surgery, and multiple fractures), pancreatitis,and transfusion reactions
ADD A FOOTER 10 11  MORPHOLOGY ACUTE PHASE ORGANIZING STAGE ACUTE PHASE: Lungs are dark red, firm, airless, and heavy Microscopy: capillary congestion, necrosis of alveolar epithelial cells, interstitial, intraalveolar edema, hemorrhage, and (particularly with sepsis) Collections of neutrophils in capillaries. Most characteristic finding: hyaline membranes 12 13  MORPHOLOGY ACUTE PHASE ORGANIZING STAGE ORGANIZING STAGE:  Type II pneumocytes proliferation.  Fibrin-rich exudates organize into intra alveolar fibrosis  Marked thickening of the alveolar septa
14 15  Clinical Features Severe ARDS is characterized by rapid onset of life threatening respiratory insufficiency, cyanosis, and severe arterial hypoxemia that is refractory to oxygen therapy. In 85% of cases, it develops within 72 hours of the initial insult. The overall hospital mortality rate is 38.5% (27%, 32%, and 45% for mild, moderate, and severe ARDS, respectively). 16 Respiratory failure occurring: Within 1 week of a known clinical insult Bilateral opacities on chest imaging Not fully explained by: effusions
atelectasis
cardiac failure fluid overload 17 OBSTRUCTIVEVERSUS RESTRICTIV E
PULMONARY DISEASES 18  Diffuse pulmonary diseases Obstructive (airway) Restrictive disease disease * Characterized by an increase in * Characterized by reduced expansion resistance to air flow caused by partial or of lung parenchyma and decreased complete obstruction at any level total lung capacity (1) Chest wall disorders (severe obesity, diseases of the pleura, and neuromuscular Examples Emphysema Chronic bronchitis disorders, such as the Guillain-Barré syndrome) Bronchiectasis Asthma (2) acute or chronic interstitial lung diseases. ARDS/pneumoconiosis/interstitial fibrosis of
unknown etiology ,…. (FVC)= normal or slightly decreased (FEV1)= significantly decreased (FVC)= reduced (FEV1)= normal or reduced FEV to FVC = Decreased FEV to FVC = near normal OBSTRUCTIVE LUNG (AIRWAY) DISEASES Chronic obstructive pulmonary disease (COPD): chroni c irreversibl e obstruction usually coexist cigarette smoking 21 ADD A FOOTER 22  Emphysema is defined on the Chronic bronchitis is defined basis of morphologic and on the basis of clinical radiologic features. features. 23  Emphysema Emphysema is characterized by permanent enlargement of the air spaces distal to the terminal bronchioles: ACCOMPANIED BY DESTRUCTION of their walls WITHOUT SIGNIFICANT FIBROSIS. 24 Four major types of emphysema: (1) Centriacinar Significant airway (2) Panacinar obstruction (3) Distal acinar (4) Irregular The most common form
25  Centri acinar More common and severe in the upper lobes (particularly apical segments). Most common in cigarette smokers. 26  Panacinar Occurs more commonly in the lower lung zones Associated with α1-anti-trypsin deficiency 27 Distal acinar (para septal) The proximal portion of the acinus is normal but the distal part is primarily involved. More striking adjacent to the pleura 28 Irregular Acinus is irregularly involved Associated with scarring Clinically asymptomatic The most common form 29 Pathogenesis Protease-mediated damage of extracellular matrix has a central role in the airway obstruction seen in emphysema. 30  MORPHOLO GY There is marked enlargement of the air spaces, with destruction of alveolar septa but without fibrosis. 31 32  Clinical Features Dyspnea usually is the first symptom; it begins insidiously
but is steadily progressive. In patients with underlying
chronic bronchitis or chronic asthmatic bronchitis, cough
and wheezing may be the initial complaints. Weight loss is
common and may be severe enough to suggest an occult
malignant tumor. Pulmonary function tests reveal reduced
FEV1 with normal or near-normal FVC. Hence, the FEV1 to
FVC ratio is reduced
33 barrel-chested and dyspneic, with obviously prolonged
expiration, sitting forward in a hunched-over position.
Dyspnea and hyperventilation are
prominent, so that until very late in the disease, gas
exchange is adequate and blood gas values are relatively
normal. Because of prominent dyspnea and adequate oxygenation of hemoglobin, these patients sometimes are
sometimes called “pink puffers.”
34  Attention! Conditions Related to Emphysema Compensatory emphysema (after surgical removal of a diseased lung or lobe ) Obstructive overinflation Bullous emphysema (spaces >1 cm) Mediastinal (interstitial) emphysema 36  Mediastinal (interstitial) emphysema Bullous emphysema with large apical and subpleural bullae
37 Chronic Bronchitis Presence of a persistent productive cough for at least 3 consecutive months in at least 2 consecutive years. Common among cigarette smokers and urban dwellers in smog -ridden cities (20% to 25% of men in the 40- to 65-year-old age). 38  Pathogenesis:  Most important cause is cigarette smoking, other air pollutants, such as sulfur dioxide and nitrogen dioxide  Induce hypertrophy of MUCOUS GLANDS in the trachea and mucin-secreting GOBLET CELLS
 These irritants also cause inflammation marked by the infiltration of macrophages, neutrophils, and lymphocytes
39 The airflow obstruction in chronic bronchitis results from: (1) Small airway disease, induced by:Mucous plugging of the bronchiolar lumen Inflammation Bronchiolar wall fibrosis (2) Coexistent emphysema 40  MORPHOLOGY The diagnostic feature in trachea and larger bronchi : Enlargement of the mucus secreting glands Ratio of the thickness of the submucosal gland layer to that of the bronchial wall (Reid index: normally 0.4). Variable numbers of inflammatory cells, large lymphocytes and macrophages but sometimes. 41 42  SMALL AIRWAY DISEASE  Goblet cell metaplasia  Mucous plugging  Inflammation  Fibrosis
In severe cases: complete obliteration of the lumen (bronchiolitis obliterans). 43 44 CLINICAL FEATURES The course of chronic bronchitis is quite variable: In some: cough and sputum production persist indefinitely without ventilatory dysfunction Others: COPD with significant outflow obstruction marked by hypercapnia, hypoxemia, and cyanosis Poorer outcomes than those with emphysema alone. Progressive disease is marked by: development of pulmonary hypertension, sometimes leading to cardiac failure. 45  Asthma Recurrent episodes of wheezing Breathlessness Chest tightness Cough Asthma is a chronic inflammatory disorder of the airways that causes: Particularly at night and/or early in the morning 46 The hallmarks of asthma: Intermittent, reversible airway obstruction Chronic bronchial inflammation with eosinophils Bronchial smooth muscle cell hypertrophy Hyperreactivity Increased mucus secretion 47  Of note, asthma has increased in incidence significantly in the Western world over the past 4 decades. One explanation for this troubling trend is the hygiene hypothesis, according to which a lack of exposure to infectious organisms (and possibly nonpathogenic microorganisms as well) in early childhood results in defects in immune tolerance and subsequent hyperreactivity to immune stimuli later in life. 48 PATHOGENESIS: Major factors contributing to the development of asthma include genetic predisposition to type I hypersensitivity (atopy), acute and chronic airway inflammation, and bronchial hyperresponsiveness to a variety of stimuli. 49  Asthma may be subclassified as: 1) Atopic (evidence of allergen sensitization) 2) Nonatopic In both types, episodes of bronchospasm may be triggered by diverse exposures, such as respiratory infections (especially viral ), airborne irritants (e.g., smoke, fumes), cold air, stress, and exercise. 50 Atopic Asthma Most common type of asthma (type I IgE–mediated hypersensitivity reaction). Usually begins in childhood (allergic rhinitis, urticaria, or eczema) Attacks triggers: allergens in dust, pollen, animal dander, food, infections. A positive family history A skin test: Immediate wheal-and-flare reaction. 51  Non-Atopic Asthma Do not have evidence of allergen sensitization Skin test: Negative Family history of asthma: Negative Common triggers: Respiratory infections due to viruses Inhaled air pollutants Ultimate humoral and cellular mediators of airway obstruction (e.g., eosinophils) are common to both atopic and nonatopic variants of asthma, so they are treated in a similar way 52 The classic atopic form: SENSITIZATION ALLERGEN TRIGGERED Early (immediate) phase Late phase 53 54 4-8hr 12-24hr 55 Drug-Induced Asthma Aspirin the most striking example. Patients with aspirin sensitivity present with recurrent rhinitis, nasal polyps, urticaria, and bronchospasm. 56 Occupational Asthma Fumes (epoxy resins, plastics) Organic dusts Chemical dusts (wood, cotton, platinum) Gases (toluene) Asthma attacks usually develop after repeated exposure to the inciting antigen(s). 57  MORPHOLOGY Mucous plug The most striking finding: occlusion of bronchi and bronchioles by thick, tenacious mucous plugs containing whorls of shed epithelium (Curschmann spirals) Curschmann spirals 58 Numerous eosinophils and Charcot- Leyden crystals (crystalloids made up of the eosinophil protein galectin-10) also are present.
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