Respiratory pathology

Respiratory Pathology Overview

  • Presented by: Biniam Tsegaye (MD) Pathologist

  • Date: 17/10/2023

Outline of Topics

  • Congenital anomalies, atelectasis, and pulmonary edema

  • Respiratory distress syndrome

  • Diffuse lung disease

  • Diseases of vascular origin

  • Pulmonary infection

  • Neoplasms of lung

  • Pleural diseases

Objectives

  • Apply knowledge of various causes of respiratory diseases including:

    • Genetic

    • Developmental

    • Metabolic

    • Toxic

    • Infectious

    • Autoimmune

    • Neoplastic

    • Degenerative

    • Traumatic

  • Analyze important determinants and risk factors of common respiratory disorders.

Microscopic Structure of the Alveolar Wall

  • Structure includes:

    • Alveolar type I and II pneumocytes

    • Interstitial cells and endothelial cells

    • Basement membrane highlighted in microscopic images.

Congenital Anomalies in the Lungs

  • Developmental anomalies are rare; common ones include:

    • Pulmonary hypoplasia

    • Foregut cysts:

      • Bronchogenic (most common)

      • Esophageal

      • Enteric

    • Pulmonary sequestration:

      • Discrete lung area that lacks connection to airway system and has abnormal blood supply.

        • Types:

          • Extralobar sequestration

          • Intralobar sequestration

  • Less common anomalies:

    • Tracheal/bronchial anomalies (atresia, stenosis, tracheoesophageal fistula)

    • Vascular anomalies

    • Congenital pulmonary airway malformation

    • Congenital lobar overinflation (emphysema)

Atelectasis (Lung Collapse)

  • Represents incomplete lung expansion (neonatal atelectasis) or collapse of inflated lung.

  • Types include:

    • Resorption: Obstruction prevents air from reaching alveoli.

    • Compression: External pressure inhibits lung inflation.

    • Contraction: Fibrotic changes in the lung that prevent expansion.

Pulmonary Edema

  • Conditions leading to edema include:

  • Increased hydrostatic pressure:

    • Often due to left-sided heart failure, pulmonary vein obstruction, or volume overload.

  • Decreased oncotic pressure:

    • Less common causes include nephrotic syndrome or liver disease.

  • Alveolar wall injury:

    • Caused by direct or indirect injury (e.g., infections, exposed to inhaled gases).

    • Examples of direct injuries include infections and inhaled smoke.

  • Edema of undetermined origin:

    • High altitude effects, neurogenic events (CNS trauma).

Acute Lung Injury (ALI) and Acute Respiratory Distress Syndrome (ARDS)

  • Characteristics:

    • Abrupt hypoxemia and bilateral pulmonary infiltrates without cardiac failure.

  • Histologic manifestation:

    • Diffuse alveolar damage (DAD).

Conditions Associated with ARDS

  • Infection: sepsis, viral infections, pneumonia, aspirated gastric contents.

  • Physical/injury: trauma, pulmonary contusions, fractures, near-drowning.

  • Irritants: oxygen toxicity, chemical exposure.

Diffuse Pulmonary Diseases

Types

  • Obstructive Lung Diseases

    • Defined by increased airflow resistance.

    • Includes:

      • Emphysema

      • Chronic bronchitis

      • Asthma

      • Bronchiectasis

  • Restrictive Lung Diseases

    • Involve reduced lung expansion and decreased total lung capacity.

Common Manifestation

  • Dyspnea

Obstructive Lung Diseases

  • Examples include chronic bronchitis, emphysema, asthma, and bronchiectasis.

Emphysema

  • Characterized by destruction of airspace walls without fibrosis.

Chronic Bronchitis

  • Defined as a persistent cough with sputum production for at least 3 months in 2 consecutive years without other identifiable causes.

    • Reid Index (normal is 0.4).

Asthma

  • Chronic disorder characterized by episodic bronchoconstriction due to airway hypersensitivity and inflammation.

    • Types include atopic and non-atopic asthma.

Bronchiectasis

  • A permanent dilation of bronchi resulting from chronic necrotizing infections leading to smooth muscle destruction.

Interstitial (Restrictive) Lung Diseases

  • Characterized by inflammation and fibrosis. Examples include pneumoconiosis and interstitial fibrosis.

Pneumoconioses

  • A non-neoplastic lung disease due to inhalation of mineral dusts, including treatment and identification of specific dusts:

    • Coal dust, silica, and asbestos-related diseases.

Pulmonary Infections

  • Various forms of pneumonia categorized by source and causative organism:

    • Community-acquired, nosocomial, aspiration, and in immunocompromised individuals.

Lung Cancers

  • Predominantly related to smoking with various types:

    • Squamous cell carcinoma, adenocarcinoma, small cell carcinoma.

Mesothelioma

  • A malignant tumor associated with asbestos exposure leading to a high rate of mortality.

Conclusion

  • Respiratory pathology encompasses various congenital anomalies, infections, diseases of vascular origin, and neoplasms. Understanding these components is essential for diagnosis and treatment.