Respiratory neoplasms

Respiratory System

Objectives

  • Overview of the respiratory system encompassing its anatomy, functions, histology, infections, immune disorders, and neoplasms.

Introduction

  • All living organisms possess a form of respiratory system to facilitate gas exchange.

  • The core function across organisms is the same: gas exchange, but anatomy and physiological processes vary significantly.

    • Birds: Lack a diaphragm and pleural cavity.

    • Amphibians: Utilize skin for gas exchange, aided by highly vascularized and moist skin with specialized mucus-secreting cells.

    • Fish: Utilize gills for oxygen extraction from water.

    • Plants: Employ diffusion through stomata located under leaves to intake carbon dioxide (CO2) for photosynthesis, producing oxygen (O2).

Anatomy & Function

  • Upper Respiratory Tract:

    • Comprises the nasopharynx, oropharynx, and larynx.

    • Function: Serves as the entry point for air; warms and moistens the air; lined with mucosa that traps bacteria and foreign particles.

  • Middle Respiratory Tract:

    • Consists of the trachea.

    • Function: Pathway for air travel from the upper tract to pulmonary regions.

  • Lower Respiratory Tract:

    • Includes the left and right primary bronchi, bronchioles, and lungs.

    • Function: Gas exchange facilitates the transfer of gases between the body and environment.

  • Airway Bifurcation:

    • The trachea bifurcates into right and left primary bronchi.

    • Primary bronchi further branch into bronchioles.

    • Bronchioles branch into alveolar ducts, culminating in alveoli.

  • Acinus:

    • Defined as the functional unit of the lung that encompasses terminal bronchioles and alveoli.

    • Comprising 5 to 7 acini forms a pulmonary lobule, which is surrounded by connective tissue, creating pulmonary lobes.

    • Right lung: 3 pulmonary lobes; Left lung: 2 pulmonary lobes.

PLEURA

  • Structure surrounding the lungs, featuring a serous membrane that forms two layers:

    • Visceral pleura: Adhered to lungs.

    • Parietal pleura: Lining of the thoracic cavity.

  • Pleural Space: The area between the pleurae, filled with pleural fluid, enabling smooth movement during respiration.

Histology

  • Nasal passages: Lined with cuboidal epithelium featuring ciliated mucus-producing cells, functions to moisten and filter incoming air.

  • Pharynx & Larynx: Comprised of squamous cell epithelium, with lymphoid tissue in the pharynx and a cartilaginous structure in the larynx, which is crucial for voice production.

  • Trachea & Bronchi: Features cuboidal epithelium with cartilaginous rings and smooth muscle.

  • Alveoli: Contain specialized cells called pneumocytes.

Normal Respiration Requirements

  • Condition for Normal Respiration:

    • Airways must remain patent (open and unobstructed).

    • Lungs must expand rhythmically.

    • The alveolar respiratory membrane must remain intact.

    • Central nervous system (CNS), thoracic muscles, and diaphragm coordination must function properly.

  • Impediments: Any deviation from these conditions leads to impeded respiration known as dyspnea.

Infections

  • Types of Infections:

    • Upper respiratory infections.

    • Pneumonia.

    • Chronic Obstructive Pulmonary Disease (COPD).

Upper Respiratory Infections

  • Primarily caused by viruses; commonly referred to as the "cold" or "flu".

  • Characteristics:

    • Short-lived and heal spontaneously.

    • Antibiotics are ineffective.

    • No substantial evidence links cold temperatures or damp weather to increased URI occurrence.

  • Contributors: Physical exhaustion, old age, and poor health increase susceptibility to these infections; viral URIs may lead to secondary bacterial infections such as streptococcal nasopharyngitis.

Viral Symptoms

  • Symptoms indicative of viral infections include:

    • Nasal congestion.

    • Rhinorrhea (runny nose).

    • Throat pain or discomfort upon swallowing.

    • Sneezing.

    • Hacking cough.

    • Malaise.

    • Mild fever.

Bacterial Symptoms

  • Symptoms seen in bacterial infections include:

    • Purulent (pus) nasal discharge.

    • Sinus/ear pain.

    • Deep throat expectoration (coughing up phlegm).

  • Bacterial infections require antibiotics over 7 to 10 days; incomplete treatment could lead to complications such as rheumatic fever or acute glomerulonephritis.

Pneumonia

  • Defined as lung inflammation. Two primary types include:

    • Alveolar Pneumonia: Primarily correlates with intra-alveolar inflammation, often viral in origin.

    • Interstitial Pneumonia: Affects alveolar septa, typically bacterial, and commonly bilateral, often seen in patients with general debilitation, elderly patients, or those with pulmonary edema or heart failure.

Pneumonia Pathophysiology

  • When pneumonia occurs, oxygen (O2) is unable to reach the bloodstream due to fluid filling air spaces in the alveoli.

Risk Factors for Pneumonia

  • Commonly seen in:

    • Debilitated patients.

    • Elderly patients over 70.

    • Children under 5.

    • Smokers.

    • Alcoholics.

    • Immunosuppressed individuals, such as AIDS patients.

Symptoms of Pneumonia

  • Viral Symptoms: Fever, dry cough, headache, muscle pain, weakness, shaking chills, chattering teeth, severe chest pain.

  • Bacterial Symptoms: Cough that produces rust-colored or greenish mucus, high fever, sweating, rapid breathing, rapid pulse rate.

Pneumonia Pathogens

  • Pneumonia may be caused by various pathogens including:

    • Bacteria (75% of cases).

    • Viral agents.

    • Fungal agents.

    • Protozoa.

    • Parasites.

Pathogen Entry to Lungs

  • Pathogens reach the lungs through:

    • Inhalation of airborne droplets.

    • Aspiration of infected particles from gastric contents (especially in unconscious patients).

    • Hematogenous spread, where pathogens are transported through blood (e.g., during sepsis).

Diagnosing Pneumonia

  • Clinically, pneumonia is classified as:

    • Primary (community-acquired).

    • Secondary (hospital-acquired).

    • Imaging Studies: Chest X-ray (CXR), CT, MRI; to determine the location and extent of pneumonia.

    • Sputum Cultures: Identifying pathogens involved.

    • Blood Cultures: Assess whether the pathogen spread via blood.

Treatment of Pneumonia

  • Bacterial Pneumonia: Treated with antibiotics; support lung function.

  • Viral Pneumonia: Usually heals spontaneously.

Complications of Pneumonia

  • Possible complications due to aggressive pathogens or ineffective treatment include:

    • Pleuritis: Inflammation spreading to the pleura, leading to pleural effusion, inhibiting lung expansion.

    • Abscess Formation: Occurs due to aggressive bacteria leading to destruction of lung parenchyma.

    • Chronic Lung Disease: Characterized by pneumonia resistant to treatment leading to fibrotic lung alterations known as "honey comb lung".

Chronic Obstructive Pulmonary Disease (COPD)

  • Definition: Any disease leading to airway obstruction, encompassing chronic bronchitis and emphysema.

  • Pathology: Begins in the submucosa with hyperplasia of mucus glands, chronic inflammation, and fibrosis.

Chronic Bronchitis

  • Defined as long-term irritation of bronchial tubes leading to excessive tracheobronchial mucus production, causing chronic cough and mucus expectoration. Criteria for diagnosis require symptoms to persist for 3 months over 2 consecutive years.

Causes of Chronic Bronchitis

  • Predominantly caused by smoking (90% of diagnoses), with a direct correlation between smoking amount and disease frequency.

  • Cessation of smoking alleviates symptoms.

  • Other causes include air pollution, toxic fume exposure, recurrent respiratory infections, and childhood viral pneumonia, which increases susceptibility.

Emphysema

  • Definition: Characterized by enlargement of air spaces throughout the lungs and destruction of alveolar walls, resulting in large air cysts with poor oxygenation because trapped air within these cysts leads to lower gas exchange efficiency.

Mechanism of Emphysema Development

  • Irritants from smoke incite an inflammatory response, leading to leukocyte influx that releases proteolytic enzymes, damaging alveolar walls. The presence of O2 radicals from smoking exacerbates damage, generating more inflammatory response, which further compromises lung structure.

Risk Factors for Emphysema

  • Key risk factor: chronic cigarette smoking.

  • Genetic deficiency in alpha-1 antitrypsin, crucial for lung protection, significantly increases risk.

  • Treatment primarily focuses on managing symptoms and avoiding smoke exposure.

Symptoms of Emphysema

  • Blue Bloaters: Retentions of carbon dioxide leading to cyanosis due to hypoxia, chronic cough with mucus expectoration, and dyspnea.

  • Pink Puffers: Characterized by progressive shortness of breath without significant mucus production.

Treatment for Emphysema

  • Supportive measures to sustain quality of life; irreversible damage necessitates palliative care focused on symptom relief, regardless of smoking cessation.

Immune Diseases

  • Common immune diseases include:

    • Allergic rhinitis (hay fever).

    • Bronchial asthma.

    • Sarcoidosis.

    • Hypersensitivity pneumonitis.

Allergic Rhinitis

  • Common allergic condition where nasal mucosa reacts to external allergens, with pollen as the most frequent trigger.

  • Symptoms: Hay fever symptoms arise from mast cell histamine release: sneezing, nasal congestion, rhinorrhea, itchy eyes, and fatigue.

  • Treatment: Antihistamines and nasal sprays.

Asthma

  • Defined as heightened bronchial sensitivity to various stimuli, which may be exogenous (allergens) or intrinsic (e.g., heat, exercise, irritants).

  • Affects approximately 10% of children and 5% of adults, with a 2:1 male predominance in prevalence.

Signs of an Asthma Attack

  • Include shortness of breath, wheezing, chest tightness, and coughing.

Asthma's Effect on Breathing

  • During an asthma attack, bronchial muscle constriction and inflammation hinder airflow, whereas non-asthmatic individuals maintain open air passages facilitating easy air entry.

Asthma Treatment

  • Focused on prevention and management of bronchospasms utilizing medications.

Neoplasms

  • Types of Neoplasms:

    • Carcinoma of the larynx.

    • Lung carcinoma.

Larynx Carcinoma

  • Epidemiology/Etiology: >95% are squamous cell carcinomas (SCC), prevalent among males aged 50-60; heavily correlated with smoking, voice strain, and alcohol consumption.

    • Most common cancer in the aerodigestive tract with primarily glottic lesions

Histology of Laryngeal Carcinomas

  • More differentiated lesions found in glottic lesions, while supraglottic lesions are less differentiated and more aggressive, frequently leading to positive cervical lymph node involvement.

Symptoms & Diagnosis of Laryngeal Carcinoma

  • Symptoms include hoarseness, respiratory stridor, and persistent sore throat.

  • Diagnostic methods utilize indirect laryngoscopy, fiberoptic endoscopy, biopsies, and imaging studies for staging and grading.

Treatment of Laryngeal Carcinoma

  • Treatment is based on vocal cord mobility; early stages respond well to radiation while advanced cases may require laryngectomy, necessitating a tracheostomy.

Routes of Spread for Laryngeal Carcinoma

  • Supraglottic lesions are particularly aggressive towards cervical lymph nodes, showing 40-50% involvement at diagnosis.

Prognosis for Laryngeal Carcinoma

  • Survival rates:

    • Glottic lesions: 80-90% without cord fixation, 50-60% with fixation.

    • Supraglottic lesions: 60-70% with node involvement, 30-50% with node-negative status.

Lung Carcinoma

  • Overall Facts: Leading cause of cancer-related deaths in the US, with a significant link to smoking.

  • Risk Factors: Include cigarette smoking, occupational exposures (e.g., coal tar, nickel), and environmental exposure (radon gas).

Cell Types in Lung Cancer

  • Types Include:

    • Small Cell Lung Cancer: Centrally located, commonly presents at an advanced stage, linked to smoking, and has the poorest prognosis.

    • Non-Small Cell Lung Cancer: Encompasses adenocarcinomas and large cell types, typically peripheral.

    • Mesothelioma: Associated with asbestos exposure, may have a long latency period.

Symptoms of Lung Cancer

  • Local Symptoms: Cough, hemoptysis, dyspnea, and chest pain.

  • Regional Symptoms: Pain, coughing, dyspnea, and dysphagia.

  • Metastatic Symptoms: Anorexia, fatigue, and hypertrophic pulmonary osteoarthropathy (evidenced by clubbing of the fingertips).

Lung Cancer Diagnosis

  • Through thorough history, physical examination, and radiographic imaging (CXR, CT, MRI, PET) to confirm and stage metastasis.

Lung Cancer Treatment

  • Treatment options include:

    • Surgery: Reserved for surgical candidates with limited disease (i.e., absence of pleural effusion or mediastinal involvement).

    • Radiation Therapy: For patients who are non-surgical candidates, often as part of palliative treatment plans.

Spread of Lung Cancer

  • Local Spread: May direct involve ribs, heart, esophagus, and spine.

  • Lymphatic Spread: Involvement of mediastinal and cervical lymph nodes.

  • Hematogenous Spread: Metastasis to liver, brain, bones, adrenal glands, kidneys, and other lung areas.

Patient Prognosis

  • Overall 5-year survival rates:

    • Non-Small Cell Lung Carcinoma (23%).

    • Small Cell Lung Carcinoma (6%).

    • Survival rates are gradually improving with advancements in treatment techniques.


Objectives

  • Understand the respiratory system's anatomy, functions, histology, infections, immune disorders, and neoplasms.

Introduction

  • All living organisms perform gas exchange.

  • While the core function is universal, anatomy and physiology vary:

    • Birds: Lack diaphragm and pleural cavity.

    • Amphibians: Use skin (vascularized, moist, mucus-secreting cells) for gas exchange.

    • Fish: Use gills for O2 extraction from water.

    • Plants: Use stomata (under leaves) for CO2 intake in photosynthesis, releasing O2.

Anatomy & Function

  • Upper Respiratory Tract:

    • Parts: Nasopharynx, oropharynx, larynx.

    • Function: Air entry; warms/moistens air; mucosa traps particles.

  • Middle Respiratory Tract:

    • Part: Trachea.

    • Function: Air pathway to lungs.

  • Lower Respiratory Tract:

    • Parts: Primary bronchi (left/right), bronchioles, lungs.

    • Function: Gas exchange between body and environment.

  • Airway Bifurcation:

    • Trachea →\rightarrow Primary bronchi →\rightarrow Bronchioles →\rightarrow Alveolar ducts →\rightarrow Alveoli (gas exchange units).

  • Acinus:

    • Definition: Functional unit of the lung (terminal bronchioles + alveoli).

    • 5-7 acini form a pulmonary lobule.

    • Pulmonary lobules (surrounded by connective tissue) form pulmonary lobes.

    • Right lung: 3 lobes; Left lung: 2 lobes.

PLEURA

  • Serous membrane surrounding lungs, with two layers:

    • Visceral pleura: Adhered to lungs.

    • Parietal pleura: Lines thoracic cavity.

  • Pleural Space: Area between pleurae, contains pleural fluid for smooth respiratory movement.

Histology

  • Nasal passages: Cuboidal epithelium with ciliated mucus-producing cells (moisten, filter air).

  • Pharynx & Larynx: Squamous cell epithelium; pharynx has lymphoid tissue; larynx is cartilaginous (voice).

  • Trachea & Bronchi: Cuboidal epithelium, cartilaginous rings, smooth muscle.

  • Alveoli: Contain specialized pneumocytes.

Normal Respiration Requirements

  • For normal respiration, these four conditions must be met:

    • Airways are patent (open, unobstructed).

    • Lungs expand rhythmically.

    • Alveolar respiratory membrane remains intact.

    • CNS, thoracic muscles, and diaphragm coordinate properly.

  • Any deviation leads to dyspnea (impeded respiration).

Infections

  • Types:

    • Upper Respiratory Infections (URIs)

    • Pneumonia

    • Chronic Obstructive Pulmonary Disease (COPD)

Upper Respiratory Infections (URIs)

  • Cause: Primarily viruses (common cold/flu).

  • Characteristics:

    • Short-lived, self-healing.

    • Antibiotics ineffective.

    • No link to cold/damp weather.

  • Risk Factors: Physical exhaustion, old age, poor health, viral URIs can lead to secondary bacterial infections (e.g., strep nasopharyngitis).

Viral URI Symptoms

  • Nasal congestion

  • Rhinorrhea (runny nose)

  • Throat pain/discomfort upon swallowing

  • Sneezing

  • Hacking cough

  • Malaise

  • Mild fever

Bacterial URI Symptoms

  • Purulent (pus) nasal discharge

  • Sinus/ear pain

  • Deep throat expectoration (coughing up phlegm)

  • Treatment: Require antibiotics (7-10 days); incomplete treatment risks complications (rheumatic fever, glomerulonephritis).

Pneumonia

  • Definition: Lung inflammation.

  • Two Primary Types:

    • Alveolar Pneumonia: Intra-alveolar inflammation, often viral.

    • Interstitial Pneumonia: Affects alveolar septa, typically bacterial, often bilateral, common in debilitated/elderly patients, or those with pulmonary edema/heart failure.

Pneumonia Pathophysiology

  • Fluid fills alveoli, preventing O2 from reaching the bloodstream.

Risk Factors for Pneumonia

  • Debilitated patients

  • Elderly patients (>70>70)

  • Children (<5<5)

  • Smokers

  • Alcoholics

  • Immunosuppressed (e.g., AIDS patients)

Symptoms of Pneumonia

  • Viral Symptoms: Fever, dry cough, headache, muscle pain, weakness, shaking chills, chattering teeth, severe chest pain.

  • Bacterial Symptoms: Cough with rust-colored or greenish mucus, high fever, sweating, rapid breathing, rapid pulse rate.

Pneumonia Pathogens

  • Causes: Bacteria (75%), viruses, fungi, protozoa, parasites.

Pathogen Entry to Lungs

  • Inhalation of airborne droplets.

  • Aspiration of infected gastric contents (e.g., in unconscious patients).

  • Hematogenous spread (via blood, e.g., during sepsis).

Diagnosing Pneumonia

  • Classification: Primary (community-acquired) or Secondary (hospital-acquired).

  • Methods:

    • Imaging: CXR, CT, MRI (location, extent).

    • Sputum Cultures: Identify pathogens.

    • Blood Cultures: Check for hematogenous spread.

Treatment of Pneumonia

  • Bacterial: Antibiotics, support lung function.

  • Viral: Usually heals spontaneously.

Complications of Pneumonia

  • Pleuritis: Inflammation spreads to pleura →\rightarrow pleural effusion →\rightarrow inhibits lung expansion.

  • Abscess Formation: Aggressive bacteria destroy lung parenchyma.

  • Chronic Lung Disease: Pneumonia resistant to treatment →\rightarrow fibrotic lung alterations (e.g., "honeycomb lung").

Chronic Obstructive Pulmonary Disease (COPD)

  • Definition: Any disease causing airway obstruction (chronic bronchitis + emphysema).

  • Pathology: Submucosal hyperplasia of mucus glands, chronic inflammation, fibrosis.

Chronic Bronchitis

  • Definition: Long-term bronchial irritation →\rightarrow excessive tracheobronchial mucus production →\rightarrow chronic cough and mucus expectoration.

  • Diagnosis: Symptoms persist for 3 months over 2 consecutive years.

Causes of Chronic Bronchitis

  • Smoking: Predominant cause (90%), directly correlated with amount smoked. Cessation alleviates symptoms.

  • Other: Air pollution, toxic fume exposure, recurrent respiratory infections, childhood viral pneumonia.

Emphysema

  • Definition: Enlarged air spaces and destroyed alveolar walls →\rightarrow large air cysts with poor oxygenation (trapped air reduces gas exchange).

Mechanism of Emphysema Development

  • Smoke irritants →\rightarrow inflammatory response →\rightarrow leukocyte influx →\rightarrow proteolytic enzymes damage alveolar walls.

  • O2 radicals from smoking exacerbate damage, increasing inflammation and compromising lung structure.

Risk Factors for Emphysema

  • Chronic cigarette smoking (key).

  • Genetic deficiency in alpha-1 antitrypsin (crucial for lung protection) dramatically increases risk.

  • Treatment: Symptom management, avoiding smoke exposure.

Symptoms of Emphysema

  • Blue Bloaters (Chronic Bronchitis predominance):

    • CO2 retention →\rightarrow cyanosis (due to hypoxia).

    • Chronic cough with mucus expectoration.

    • Dyspnea.

  • Pink Puffers (Emphysema predominance):

    • Progressive shortness of breath.

    • No significant mucus production.

Treatment for Emphysema

  • Supportive palliative care focused on symptom relief; irreversible damage.

Immune Diseases

  • Common types:

    • Allergic rhinitis (hay fever)

    • Bronchial asthma

    • Sarcoidosis

    • Hypersensitivity pneumonitis

Allergic Rhinitis

  • Definition: Nasal mucosa reacts to allergens (pollen most common).

  • Symptoms (due to mast cell histamine release): Sneezing, nasal congestion, rhinorrhea, itchy eyes, fatigue.

  • Treatment: Antihistamines, nasal sprays.

Asthma

  • Definition: Heightened bronchial sensitivity to stimuli (exogenous allergens, intrinsic factors like heat/exercise/irritants).

  • Prevalence: 10%10\% children, 5%5\% adults (2:1 male predominance).

Signs of an Asthma Attack

  • Shortness of breath, wheezing, chest tightness, coughing.

Asthma's Effect on Breathing

  • Bronchial muscle constriction and inflammation hinder airflow during attacks, unlike open passages in non-asthmatics.

Asthma Treatment

  • Prevention and management of bronchospasms with medications.

Neoplasms

  • Types:

    • Carcinoma of the larynx

    • Lung carcinoma

Larynx Carcinoma

  • Epidemiology/Etiology: >95%95\% are Squamous Cell Carcinomas (SCC).

    • Prevalent in males aged 50−6050-60.

    • Strongly linked to smoking, voice strain, alcohol consumption.

    • Most common cancer in the aerodigestive tract; primarily glottic lesions.

Histology of Laryngeal Carcinomas

  • Glottic lesions: More differentiated.

  • Supraglottic lesions: Less differentiated, more aggressive, frequent cervical lymph node involvement.

Symptoms & Diagnosis of Laryngeal Carcinoma

  • Symptoms: Hoarseness, respiratory stridor, persistent sore throat.

  • Diagnosis: Indirect laryngoscopy, fiberoptic endoscopy, biopsies, imaging (staging/grading).

Treatment of Laryngeal Carcinoma

  • Based on vocal cord mobility.

  • Early stages: Respond to radiation.

  • Advanced cases: May require laryngectomy and tracheostomy.

Routes of Spread for Laryngeal Carcinoma

  • Supraglottic lesions: Aggressive towards cervical lymph nodes (40-50% involvement at diagnosis).

Prognosis for Laryngeal Carcinoma

  • Glottic lesions: 80−90%80-90\% (without cord fixation), 50−60%50-60\% (with fixation).

  • Supraglottic lesions: 60−70%60-70\% (with node involvement), 30−50%30-50\% (with node-negative status).

Lung Carcinoma

  • Overall Facts: Leading cause of cancer-related deaths in the US; strong link to smoking.

  • Risk Factors: Cigarette smoking, occupational exposures (coal tar, nickel), environmental (radon gas).

Cell Types in Lung Cancer

  • Small Cell Lung Cancer (SCLC):

    • Centrally located.

    • Often advanced at presentation.

    • Linked to smoking.

    • Poorest prognosis.

  • Non-Small Cell Lung Cancer (NSCLC):

    • Includes adenocarcinomas and large cell types.

    • Typically peripheral.

  • Mesothelioma:

    • Associated with asbestos exposure.

    • Can have long latency.

Symptoms of Lung Cancer

  • Local: Cough, hemoptysis, dyspnea, chest pain.

  • Regional: Pain, coughing, dyspnea, dysphagia.

  • Metastatic: Anorexia, fatigue, hypertrophic pulmonary osteoarthropathy (clubbing of fingertips).

Lung Cancer Diagnosis

  • History, physical exam, radiographic imaging (CXR, CT, MRI, PET) for confirmation and staging metastasis.

Lung Cancer Treatment

  • Surgery: For surgical candidates with limited disease (no pleural effusion or mediastinal involvement).

  • Radiation Therapy: For non-surgical candidates, often palliative.

Spread of Lung Cancer

  • Local: Direct invasion of ribs, heart, esophagus, spine.

  • Lymphatic: Mediastinal and cervical lymph nodes.

  • Hematogenous: Metastasis to liver, brain, bones, adrenal glands, kidneys, other lung areas.

Patient Prognosis

  • Overall 5-year survival rates:

    • Non-Small Cell Lung Carcinoma (23%23\%).

    • Small Cell Lung Carcinoma (6%6\%).

  • Survival rates are gradually improving.