CH 3 PART 2- Comprehensive Study Notes on Diffuse Lung Disease, Neoplasms, and Vascular Respiratory Disorders

Chronic Obstructive Pulmonary Disease (COPD)

• Overview of COPD

  • Definition: COPD is a common and treatable lung disease characterized by progressive airflow limitation and tissue destruction.

  • Global Impact: It is the third leading cause of death worldwide. Morbidity and mortality can be decreased by prompt diagnosis and treatment.

  • Pathophysiology: Chronic inflammation causes airway narrowing and decreased lung recoil. It is associated with structural lung changes caused by prolonged exposure to noxious particles or gases.

  • Primary Risk Factor: The most common source of exposure is cigarette smoke.

  • Coexisting Processes: COPD is characterized by two distinct disease processes that coexist to cause the obstructive process: chronic bronchitis and emphysema.

• Clinical Presentation and Diagnosis

  • Clinical Manifestations: Symptoms range from being asymptomatic to full respiratory failure. Primary symptoms include cough, dyspnea (shortness of breath), and sputum production.

  • Complications:

    • Asthma: Caused by bronchiole spasms, resulting in decreased airflow and airway obstruction.

    • Bronchiectasis: Permanent chronic dilatation of the bronchi or bronchioles.

  • Diagnostic Tools:

    • Pulmonary Function Testing (PFT): Essential for diagnosis, staging, and monitoring. Diagnosis is confirmed specifically by spirometry.

    • Imaging: Usually serves as the first step in the evaluation of the disease.

Chronic Bronchitis and Emphysema

• Chronic Bronchitis Detail

  • Definition: A long-term inflammatory condition of the airways.

  • Diagnostic Criteria: Characterized by a persistent productive cough without other identifiable causes lasting at least $3\,\text{months}$ per year for $2\,\text{consecutive years}$.

  • Mechanism: Leads to excessive mucus production, resulting in airway obstruction and inflammation.

  • Cause: Prolonged exposure to lung irritants, most commonly from smoking.

  • Clinical Manifestations: Persistent cough, sputum production, and in severe cases, shortness of breath (SOB), wheezing, and fatigue.

  • Imaging Findings:

    • Approximately half of the patients present with a normal chest radiograph.

    • Radiographs may demonstrate an increase in bronchovascular markings, a condition referred to as "dirty chest."

• Emphysema Detail

  • Definition: A progressive form of COPD characterized by persistent respiratory symptoms and airflow limitation resulting from airway or alveolar damage.

  • Pathophysiology: Results in the destruction of alveolar walls, air trapping, and impaired gas exchange. This causes lung over-inflation and leads to the formation of large air-filled sacs known as bullae.

  • Cause: Chronic and significant exposure to noxious gases, with cigarette smoking being the primary cause.

  • Clinical Manifestations: SOB, chronic cough, reduced exercise tolerance, and a physical sign known as barrel chest (increase in AP chest diameter).

  • Diagnosis: Radiographic studies are not typically indicated for diagnosis; instead, PFT (spirometry) is used.

  • Imaging Findings:

    • Chest Radiograph: Shows lung hyperinflation, flattening of the diaphragm, and increased anterior-posterior (AP) diameter. The heart often appears elongated and tubular.

    • CT: Useful for identifying bullae (air-containing cystic spaces), which may be present in subpleural regions. CT is also useful if malignancy, bronchiectasis, or surgical planning is considered.

Asthma and Bronchiectasis

• Asthma

  • Definition: A chronic inflammatory respiratory condition involving airway inflammation, intermittent airflow obstruction, and bronchial hyperresponsiveness.

  • Pathology: Leads to swelling of bronchial mucous membranes, excess mucus secretion, and spasms of the bronchial walls.

  • Onset: Often presents in childhood.

  • Hallmark Symptoms: Intermittent dyspnea, cough, and wheezing.

  • Triggers for Attacks:

    • Allergens: House dust, pollen, molds, animal dander, certain fabrics, and various foods.

    • Environmental/Internal factors: Exercise, exposure to heat or cold, emotional upset, and viral infections.

  • Imaging:

    • Acute: Radiographs show increased volume of hyperlucent lungs, flattening of the diaphragm, and increased retrosternal air space.

    • Chronic: Prominent interstitial markings described as "dirty chest."

  • Treatment:

    • Bronchodilators.

    • Inhaled steroid drugs.

    • Oral medications to decrease bronchial muscular spasms.

• Bronchiectasis

  • Definition: Chronic lung disease involving permanent widening of the bronchial airways due to the destruction of the elastic and muscular components of the bronchial wall.

  • Cause: Repeated infections that contribute to bacterial invasion and mucus pooling throughout the bronchial tree.

  • Complications: Pneumonia, lung abscess, empyema, septicemia, cor pulmonale, respiratory failure, secondary amyloidosis with nephrotic syndrome, and recurrent pleurisy.

  • Clinical manifests: Productive cough, dyspnea, intermittent wheezing, hemoptysis, and chest pain (CP).

  • Prognosis and Prevention: Treatable with antibiotics but rarely curable. It is preventable with vaccination.

  • Imaging:

    • Chest Radiograph: Initial study; shows coarseness and loss of definition in interstitial markings.

    • CT: More sensitive; reveals multiple dilated bronchi, producing the hallmark signet-ring sign.

Sarcoidosis and Pneumoconiosis

• Sarcoidosis

  • Definition: A multisystem disorder of unknown etiology, mostly affecting young adults worldwide, with higher prevalence in African Americans.

  • Pathology: Characterized by noncaseating granulomas in various organs, most notably the lungs, skin, eyes, and joints.

  • Etiology: Likely an exaggerated immune response to an undefined antigen (microbes or environmental factors) in genetically susceptible individuals.

  • Symptoms: Unexplained dry cough, CP, and SOB; however, many patients are asymptomatic.

  • Imaging Stages (Chest Radiograph):

    • Stage 1: Bilateral hilar lymphadenopathy.

    • Stage 2: Bilateral hilar lymphadenopathy combined with pulmonary infiltrates (reticular opacities).

    • Stage 3: Pulmonary infiltrates without bilateral hilar lymphadenopathy.

    • Stage 4: Pulmonary fibrosis.

  • CT Findings: More sensitive for subtle lymphadenopathy; presents the donut sign (lymphadenopathy encircling the trachea).

  • Treatment: Not indicated for asymptomatic Stage I or II. Corticosteroids are used for symptomatic or progressive Stage II or III.

• Pneumoconiosis (Occupational Lung Diseases)

  • General Features: Caused by inhaling fine particles that trigger an inflammatory reaction, leading to chronic interstitial inflammation and irreversible pulmonary fibrosis.

  • Variables: Severity depends on particle size, length of exposure, and concentration of particulates.

  • Major Types:

    1. Asbestosis: Caused by inhaling asbestos fibers (common in construction, shipping, and aerospace). Hallmark is pleural involvement (thickening and calcified pleural plaques). Calcification is pathognomonic after $20\,\text{years}$ from first exposure. Radiographs show reticulonodular infiltrates at lung bases causing "shaggy heart borders."

    2. Silicosis: The world's most prevalent occupational lung disease. Caused by silicon dioxide (crystalline silica) inhalation (mining, foundry, sandblasting). Presents as irreversible, progressive pulmonary fibrosis. Chronic silicosis typically presents $10-30\,\text{years}$ after exposure. Imaging shows multiple nodular shadows and hilar lymph node enlargement. End-stage requires a lung transplant.

    3. Anthracosis (Black Lung): Caused by overexposure to coal mine dust. Characterized by weakened musculature and dilatation. Coal dust turns lung tissue dark. TB is more common in these patients due to impaired macrophage function.

Lung Neoplasms

• Solitary Pulmonary Nodule (SPN)

  • Definition: A round or oval area in the lung smaller than $3\,\text{cm}$ ($1.2\,\text{inches}$). Often an incidental discovery.

  • Nature: Over half are benign (scars, past infections). Malignant nodules may indicate early-stage cancer or metastasis.

  • Benign vs. Malignant Characteristics:

    • Benign: Sharp margins, central densities (popcorn calcification), and absence of growth over $2\,\text{years}$.

    • Malignant: Ill-defined, irregular borders, and increased metabolic activity on PET scans.

  • Risk Factors: Smoking, COPD, previous malignancy, and advanced age.

• Bronchial Adenoma

  • Definition: Rare, low-grade malignant tumors originating in the mucous glands/ducts of the bronchi or trachea.

  • Profile: Most patients are < 50\,\text{years old}. Can be associated with Cushing syndrome.

  • Symptoms: Hemoptysis and recurring pneumonia.

  • Imaging: Centrally located discrete mass; peripheral atelectasis; tumor mass within air-filled bronchi.

• Bronchogenic Carcinoma (Lung Cancer)

  • Statistics: Leading cause of cancer death in the US and for men; second most common for women.

  • Etiology: Smoking (most common), asbestos, radiation, metal exposure, carcinogens, and pulmonary fibrosis.

  • Histological Types:

    1. Small Cell Lung Cancer (SCLC): Highly aggressive. Imaging shows non-specific hilar/perihilar masses and mediastinal widening due to lymph node enlargement. It is the most common cause of Superior Vena Cava (SVC) obstruction.

    2. Non-Small Cell Lung Cancer (NSCLC): Includes Adenocarcinoma, Squamous cell carcinoma, and Large cell carcinoma.

       • Adenocarcinoma: Most common primary lung cancer in the US. Often evolves from mucosal glands and is the most likely subtype in non-smokers. Usually occurs in lung periphery/scars.

  • Clinical Presentation:

    • Intrathoracic: Cough, hemoptysis, CP, dyspnea, hoarseness.

    • Extrathoracic (NSCLC subsets): Pancoast syndrome (shoulder, forearm, scapula, or finger pain); Horner syndrome (atrophy of hand muscles or bony destruction).

  • Imaging: Earliest sign is unilateral enlargement of the hilum. CT is superior for detecting bronchial narrowing and mediastinal lymphadenopathy.

  • Treatment: Surgical lobectomy is most common. Radiation and chemo are typically palliative.

• Pulmonary Metastases (METS)

  • Route: Hematogenous spread, lymphatic spread, or direct invasion.

  • Source: Breast, lung, colorectal cancer, uterine leiomyosarcoma, and head/neck squamous cell carcinoma.

  • Symptoms: Vomiting, low back pain, loss of appetite, shoulder pain.

Vascular Diseases

• Pulmonary Embolism (PE)

  • Definition: Obstruction of pulmonary arteries by a blood clot, commonly originating as a Deep Vein Thrombosis (DVT) in lower extremities.

  • Spectrum: PE and DVT form the spectrum of Venous Thromboembolism (VTE).

  • Diagnosis: D-dimer test (measures protein fragments), CT pulmonary angiography (diagnostic modality of choice), Ultrasound (for DVT), and Nuclear Medicine V/Q scans (measures ventilation/perfusion).

  • Clinical Signs: Dyspnea, CP, cough, syncope. Severe cases lead to right ventricular strain and hemodynamic instability.

  • Treatment: Anticoagulant therapy (first), thrombolytics, and IVC filter placement.

• Septic Embolism

  • Definition: An infected thrombus travels from a primary source (most commonly infective endocarditis) to obstruct a distant vessel.

  • Pathology: Results in ischemia and superimposed infection, leading to abscess formation.

  • Imaging: Contrast-enhanced CT is the modality of choice, showing multiple peripheral nodular infiltrates with or without cavitation.

• Pulmonary Arteriovenous Fistula (PAVM)

  • Definition: A rare congenital vascular anomaly involving abnormal communication between a pulmonary artery and vein, creating a right-to-left shunt.

  • Manifestations: Often asymptomatic in early life; clinically manifests in adulthood after decades of pressure. Risks include stroke, brain abscess, and massive hemoptysis.

  • Prognosis: Untreated PAVM has a mortality of up to $50\%$.

  • Imaging: Pulmonary angiogram is the gold standard. CT shows a soft tissue mass (commonly lower lobe) with a feeding artery and draining vein.

  • Treatment: Embolization therapy (most common/effective), surgical resection, or transplant.

Atelectasis and ARDS

• Atelectasis (Lung Collapse)

  • Definition: Partial or complete collapse of the lung or a section of it. Common postoperatively (within $72\,\text{hours}$ of general anesthesia).

  • Types:

    1. Obstructive (Resorptive): Airway obstruction (mucus plugs, tumors, foreign bodies) prevents air from reaching alveoli.

    2. Nonobstructive (Compression): External pressure from pleural effusion, pneumothorax, or tumors.

    3. Surfactant-related: Alveolar collapse due to surfactant impairment (e.g., ARDS or Neonatal RDS).

  • Imaging: Platelike horizontal lines, displacement of interlobar fissures, elevation of the ipsilateral hemidiaphragm, and shift of mediastinal structures toward the affected side.

• Acute Respiratory Distress Syndrome (ARDS)

  • Definition: Life-threatening condition with non-compliant ("stiff") lungs and poor oxygenation.

  • Pathophysiology: Capillary endothelial injury and diffuse alveolar damage cause fluid leakage into alveoli (non-cardiogenic pulmonary edema).

  • Etiology: Sepsis, trauma, aspiration, drowning, drug overdose, pancreatitis.

  • Prognosis/Treatment: $50\%$ mortality rate. Survivors heal by fibrosis. Treatment involves diuretics, oxygen, and ventilation assists.

Air Extravasation and Foreign Bodies

• Intrabronchial Foreign Bodies

  • Prevalence: 4th leading cause of death in US preschool children.

  • Clinical: Acute upper airway choking or distal obstruction mimicking asthma.

  • Diagnosis: Rigid bronchoscopy is the gold standard for diagnosis and retrieval.

  • Imaging: Expiration chest X-ray exaggerates differences; affected lungs appear overinflated/hyperlucent due to a "check valve" mechanism.

• Mediastinal Emphysema (Pneumomediastinum)

  • Definition: Air present in the mediastinum due to alveolar rupture or trauma. Air can migrate to the neck or peritoneal cavity.

  • Clinical: Retrosternal chest pain radiating to the neck/back.

  • Imaging Signs:

    • Spinnaker sign: Elevation of the thymus in pediatric patients.

    • Ring sign: Air surrounding pulmonary arteries.

• Subcutaneous Emphysema

  • Definition: Infiltration of air into the subcutaneous skin layer.

  • Clinical Hallmark: Crepitation (crackling sound) on palpation.

  • Imaging: Intermittent areas of radiolucency with a "fluffy" appearance on the exterior borders of the thoracic wall.

Pleural Disorders

• Pneumothorax

  • Definition: Accumulation of air between parietal and visceral pleurae.

  • Types:

    • Traumatic: Blunt or penetrating trauma. Tension pneumothorax is a medical emergency that shifts mediastinal structures and compresses the heart.

    • Atraumatic: Primary Spontaneous (no event) or Secondary Spontaneous (due to disease like emphysema).

  • Imaging Hallmark: A visceral pleural line outline. Pulmonary markings are absent in the hyperlucent peripheral area.

• Pleural Effusion and Empyema

  • Pleural Effusion: Abnormal fluid accumulation (from heart failure, pneumonia, etc.). Imaging shows a blunted costophrenic angle and the meniscus sign. Treatment is thoracentesis (fluid drainage) usually under ultrasound guidance.

  • Empyema: Presence of purulent fluid (pus) in the pleural space. Often a complication of bacterial pneumonia. CT and ultrasound are used for needle aspiration.

Mediastinum and Diaphragm

• Mediastinal Masses

  • Anterior: Thymus, Teratoma, Thyroid, Terrible Lymphoma (The Four T's).

  • Middle: Lymph nodes, trachea, esophagus, aortic arch anomalies.

  • Posterior: Typically neurogenic tumors (sympathetic ganglia, nerve roots).

• Diaphragmatic Disorders

  • Paralysis: Unilateral (more common) or bilateral loss of function due to phrenic nerve issues. Fluoroscopy hallmark is paradoxical movement during a "sniff test."

  • Eventration: Localized elevation/bulging of the diaphragm without a break in continuity. Caused by a lack of muscle or nerve function. Most patients are asymptomatic.