Concise Pathology Notes - Respiratory System

Case Study

• 13-month-old girl with altered general status, fever, headache, lethargy, diarrhea.
• Initial diagnosis: viral enterocolitis (COVID-19 negative).
• Re-hospitalization for cardiac investigations due to lack of improvement.
• Suspicion of myocarditis and possible congenital cardiac malformation.
• Sudden death, autopsy required by cardiologist.

Pathology of the Respiratory System

• Lesions of the Upper Respiratory Tract: Pages 545-547.
• Pathology of the Lung:
• Disorders of pulmonary air content: Atelectasis and respiratory distress syndrome (adults and newborns) - Pages 495-497, 278-279.
• Obstructive Lung Diseases: Pages 498-499, 500-506.
• Pulmonary Infections (Pneumonias): Pages 519-525.
• Injury by nontherapeutic toxic agents (drug abuse): Pages 315-317.
• Chronic Interstitial Lung Diseases and Smoking-Related Interstitial Diseases: Pages 506-508, 514-515.
• Lung Tumors: Pages 537-544.
• Pleural Diseases: Pages 544-545.

Pathology of the Nose, Middle Ear, and Paranasal Sinuses

• Etiology: Rhinoviruses, Coronavirus, Sincitial Respiratory Virus, Adeno-Enteroviruses, Coxsackievirus A, EBV, Streptococcus β-hemolytic group A.
• Rhinitis:
• Acute catarrhal rhinitis (common cold).
• Acute necrotizing rhinitis.
• Allergic rhinitis (seasonal, perennial).
• Chronic rhinitis (hyperplastic polyp, atrophic rhinitis).
• Rhinopharyngitis, Pharyngotonsillitis (infants).
• Otitis: Acute, chronic (cholesteatoma).
• Sinusitis: Acute, chronic.
• Kartagener Syndrome: Sinusitis + Bronchiectasis + Situs Inversus.
• Specific Inflammations: Tuberculosis, Syphilis, Rhinoscleroma, Fungi Rhinosporidium, Wegener’s Granulomatosis.

Rhinoscleroma

• Caused by Klebsiella Rhinoscleromatis.
• Characterized by Russel's bodies and Mikulicz cells.

Rhinophyma

• Hyperplasia of sebaceous glands.

Tumors of the Nose and Paranasal Sinuses

• Benign: Papilloma, Haemangioma, Angiofibroma, Adenoma.
• Malignant:
• Nasopharyngeal carcinomas.
• Squamous cell carcinoma (HPV).
• Undifferentiated (lymphoepithelial) carcinoma (EBV).
• Adenocarcinoma, adenoid cystic carcinoma.
• Malignant melanoma.
• Lymphomas (Burkitt lymphoma (EBV) and other Non-Hodgkin lymphomas).

Diseases of the Larynx

• Laryngeal edema (allergies, inflammations, tumors).
• Laryngeal stenosis (obstruction, compression).
• Laryngitis:
• Acute catarrhal laryngitis (viruses, allergies) and epiglottitis (Hemophilus influenzae).
• Acute pseudomembranous laryngitis (diphteric croup - Corynebacterium diphteriae).
• Acute necrotizing laryngitis.
• Chronic laryngitis with leukoplakia.
• Specific inflammations: Tuberculosis, Syphilis, Wegener’s Granulomatosis.

Tumors of the Larynx

• Benign: Papilloma, Papillomatosis (HPV 6 and 11), Singer’s node (laryngeal polyp).
• Malignant:
• Squamous cell carcinoma:
• Supraglottic (metastases in cervical lymph nodes).
• Glottic (best prognosis).
• Subglottic (rare tumor).
• Complications: Asphyxia, necrotic pneumonia, hemorrhages.
• Sarcomas, malignant lymphomas.

Congenital Disorders

• Lung hypoplasia.
• Polycystic lung.
• Kartagener’s syndrome (situs inversus + bronchiectasis + chronic rhinosinusitis + lack of the frontal sinuses - defective ciliary function).
• Cystic fibrosis.
• \alpha1-Antitrypsin deficiency.

Disorders of Lung Circulation

• Lung hyperemia.
• Lung congestion.
• Embolism, DIC.
• Lung infarction.
• Lung hemorrhages (Goodpasture syndrome).
• Pulmonary hypertension.

Bronchitis, Bronchiolitis

• Acute Bronchitis Types: Catharrhal, Muco-Purulent, Diphteric Croup, Hemorrhagic, Necrotizing, Ulcerative.
• Evolution & Complications: Healing, Chronic Bronchitis, Bronchopneumonia, Obstruction of Small Bronchi, Focal Atelectasis, Necrotizing Bronchitis, Lung Gangrene, Diphteric Croup, Asphyxia.
• Bronchiolitis - Children, Elderly Types: Purulent Bronchiolitis, Bronchiolitis Obliterans.

Obstructive vs Restrictive Lung Disorders

• Obstructive Lesions: Improper airflow due to increased pressure (partial or complete obstruction), COPD (Chronic Bronchitis, Asthma, Bronchiectasis, Emphysema).
• Restrictive Lesions: Decreased lung parenchyma expansion, decreased total pulmonary capacity. Pulmonary diseases: ARDS, Pneumoconioses, Interstitial Fibrosis, Lesions induced by Smoking and Drugs, Sarcoidosis, TB. Thoracic wall disorders: Obesity, Pleural disorders, Neurological diseases.

Chronic Obstructive Pulmonary Diseases

• Chronic bronchitis.
• Bronchial asthma.
• Bronchiectasis.
• Chronic emphysema.
• Chronic cor pulmonale
• Total surface of the lung: 80 m\textsuperscript{2}
• Air intake: 15-20,000 liters daily.

Chronic Bronchitis

• Clinical Definition: Cough + sputum for 3 months in two consecutive years.
• Etiology: Smoking, air pollution.
• Classification: Simple chronic bronchitis, chronic asthmatic bronchitis (intrinsic asthma).
• Consequences: Pneumonia, lung emphysema, lung fibrosis, bronchiectasis, chronic cor pulmonale.

Bronchial Asthma

• Episodic reversible small airways obstruction (bronchospasm + inflammation + mucus hypersecretion + edema).
• Asthmatic attacks: Acute emphysema, Status asthmaticus.
• Etiology: Atopic asthma (seasonal, familial, extrinsic), Non-atopic asthma (intrinsic), Drug-related asthma (aspirin), Occupational asthma, Allergic bronchopulmonary aspergillosis.
• Consequences: Pneumothorax, bronchiectasis, lung emphysema, CCP, prolonged status asthmaticus, death.

Bronchiectasis

• Types: Congenital, Acquired (children/adults), Diffuse and localized.
• Causes: Weakness of bronchial wall, increased bronchial pressure, fibrosis of lung parenchyma.
• Morphology: Dilatation of bronchi, mucus and pus in lumen, inflammatory infiltrate.
• Consequences: Pneumonia, lung abscesses, necrotizing bronchitis, lung fibrosis, chronic cor pulmonale, toxemia.

Pulmonary Emphysema

• Emphysema of the air spaces: Acute emphysema, vicariant (compensatory) emphysema, senile emphysema, chronic obstructive emphysema.
• Interstitial Emphysema

Atelectasis (Collapse)

• Neonatal Atelectasis: Primary atelectasis (lung anectasis - intrauterine death), Secondary atelectasis (dystelectasis).
• Acquired Atelectasis: Resorption, compression, scarring (contraction).

Respiratory Distress Syndrome

• Acute restrictive lung disease with lung dystelectasis.
• Alveoli lined by hyaline membranes.
  • Hyaline membrane disease (Infant Respiratory Distress Syndrome): preterm babies , caesarian intervention, mother’s diabetes - lack of surfactant
    • dystelectasia congestion plasma exudation hyaline membranes. treatament: surfactant - exogenus; oxygenotherapy might induces retrolenticular fibrodysplasia (preterm retinopathy) and bronchopulmonary dysplasia, intraventricular hemorrhage, necrotic enterocolitis, PAC
  • Adult respiratory distress syndrome (ARDS), shock lung
    • DIC destruction of surfactant dystelectasis hemorrhages hyaline membranes Death: 40% of patients

Illicit Drug Use - Consequences

• Compromised individual immunity influenced by drug concentrations, routes of administration, and associated substances (tobacco, alcohol).
• Heroin overdose leads to pulmonary hemorrhagic edema.
• Cocaine causes alveolar hemorrhages, cardiac arrhythmia, infarction, seizures, respiratory arrest.
• Methylphenidate results in pulmonary emphysema.
• Amphetamine causes myocarditis.

Lung-Related Adverse Drug Reactions (ADR) - Iatrogenic Lung Injury

• Unspecific symptoms: dry cough, low-grade fever, dyspnea, wheezing, hypoxemia, chest pain, fatigue, allergic reaction, rash, arthralgia. Serum: increased CD8+ lymphocytes and neutrophils + eosinophils.

Inflammations (Infections) of the Lung

• Non-specific inflammations: Pneumonia (bacterial, viral), Pulmonary fibrosis, Pneumoconioses, Purulent inflammations.
• Specific inflammations: Tuberculosis, Sarcoidosis, Mycoses.

Lobar Pneumonia

• Bacterial infection confined to one pulmonary lobe.
• Etiology: Streptococcus pneumoniae.
• Evolution:
• Congestion (prehepatization).
• Red hepatisation.
• Grey hepatisation.
• Yellow hepatisation.
• Resolution.

Bronchopneumonia

• Focal pneumonia common in children, elderly, and immunosuppressed individuals.
• Localization: Paravertebral areas, bilateral, inferior lobes.

Purulent inflammations

• Lung abscess
  * pneumonia, superinfection – lung infarction, lung tumors bronchiectasis, bronchial obstruction, aspiration septic emboli
• Lung gangrene
  • bronchogenic infection with anaerobi

Atypical community-acquired pneumonia

• Interstitial pneumonia
  • Viral pneumonia: Flue pneumonia – para-finfluenza viruses adenovirus (military), coronavirus pneumonia
  • Pneumonia with Mycoplasma pneumoniae
  • Pneumonia with chlamidiae: ornitosis, psitacosis
  • Pneumonia with Ricketsii
  • Pneumonia with Pneumocystis carinii
  • Chronic interstitial pneumonia

Chronic interstitial pneumonia

• Causes: viruses, toxic substances, radiations, drugs, collagen diseases

Tuberculosis

• Early lesions: Simon’s foci
• Aschoff-Puhl nodes, Assman’s subclavicular infiltrate

Sarcoidosis (Besnier-Boeck-Schaumann disease)

• Systemic granulomatous inflammation with unknown etiology

Lung Tumors

• Benign tumors: Chondroma, Bronchial adenoma.
• Malignant Tumors: Broncho-pulmonary carcinoma, Sarcomas, Lymphomas.

Bronchopulmonary Carcinoma

• Macroscopic types
  * Central tumors
  * Peribronchial tumors
  * Peripheral tumors
  * Pancoast Tobias tumor (apex)
  * Bronchopneumonia-like tumors
  * Intrabronchial tumors

Bronchopulmonary Carcinomas Microscopy

• Small cell lung carcinomas (SCLC)
• Non-small cell lung carcinomas (N-SCLC)
  • Squamous cell carcinoma
  • Adenocarcinomas
  • Bronchioloalveolar carcinomas
  • Large cell carcinomas

Pathology of the Pleura

• Disorders of circulation: Hydrothorax, Hemothorax, Petechiae, Chylothorax.
• Pneumothorax.
• Pleuritis: Infective pleuritis (serous, fibrinous, purulent, necrotizing, hemorrhagic).
• Tumors: Mesothelioma (benign or malignant), Metastases.