Pulmonology: Lung Cancers, COPD, Asthma, and Restrictive Lung Diseases

Comprehensive flashcards covering lung neoplasms, paraneoplastic syndromes, COPD, asthma, cystic fibrosis, interstitial lung diseases, pneumothorax, and pulmonary toxicology.

What is the most common lung cancer overall versus the most common primary lung cancer?

The most common lung cancer overall is secondary (metastatic) carcinoma. The most common primary lung cancer is Adenocarcinoma (Adeno CA).

What are the most common primary lung cancers in male smokers versus female smokers?

In male smokers, the most common primary lung cancer is Squamous Cell Carcinoma ($\text{SCC} \gg \text{Small cell lung carcinoma}$). In female smokers, the most common is Adenocarcinoma (Adeno CA).

What are the typical anatomical locations of Adenocarcinoma, Large cell carcinoma, Squamous cell carcinoma, and Small cell lung carcinoma?

Peripheral: Adenocarcinoma and Large cell carcinoma. Central: Squamous cell carcinoma (SCC) and Small cell lung carcinoma (SCLC).

Which neuroendocrine cell type is found in Small Cell Lung Carcinoma (SCLC / Oat Cell CA)?

Kulchitsky cells.

Which paraneoplastic complications and endocrine factors are classically associated with Squamous Cell Carcinoma (SCC) of the lung?

Squamous Cell Carcinoma produces PTH-related peptide (PTHrP), causing hypercalcemia ($\uparrow \text{Ca}^{2+}$) and hypophosphatemia ($\downarrow \text{PO}_4^{3-}$), which can result in renal stones. It is also associated with hypertrophic pulmonary osteoarthropathy and digital clubbing.

What paraneoplastic syndrome is classically linked to lung Adenocarcinoma?

Trousseau syndrome, caused by increased mucus production that triggers a migratory hypercoagulable state.

Which paraneoplastic syndromes and ectopic secretions are characteristic of Small Cell Lung Carcinoma (SCLC)?

1. SIADH (due to $\uparrow \text{ADH}$, presenting with dilutional hyponatremia and seizures/fits)
2. Cushing syndrome (due to ectopic $\uparrow \text{ACTH}$
3. Lambert-Eaton syndrome (muscle weakness that improves with activity)

What defines a Pancoast tumor (Superior Sulcus Tumor), and what is its most common histology?

A Pancoast tumor is any lung tumor located at the apex of the lung; it is most commonly a Squamous cell carcinoma.

What is Horner syndrome, and how does a Pancoast tumor cause it?

Horner syndrome is characterized by ptosis (drooping eyelid), miosis (constricted pupil), anhidrosis (decreased sweating), and facial flushing. It is caused by apical tumor compression of the stellate ganglion, damaging the sympathetic nerve fibers.

What clinical manifestations occur when a Pancoast tumor invades the brachial plexus versus the left recurrent laryngeal nerve?

Brachial plexus compression causes right arm pain, weakness, and muscle wasting. Left recurrent laryngeal nerve compression causes hoarseness of voice.

What condition presents with elevated JVP ($\uparrow \text{JVP}$), facial plethora (redness), and headache in a patient with an apical lung mass?

Superior Vena Cava (SVC) Syndrome.

What is the most common lung malignancy associated with asbestos exposure?

Bronchogenic carcinoma (specifically Adeno CA), which occurs more commonly than malignant mesothelioma.

Which lung cancers are identified by keratin pearls and non-specific enolase, respectively?

Keratin pearls are diagnostic of Squamous Cell Carcinoma (SCC), which frequently shows cavitation. Non-specific enolase (neuron-specific enolase) is positive on biopsy in Small Cell Lung Carcinoma (SCLC), an aggressive neuroendocrine tumor.

What are the fundamental differences in lung mechanics between obstructive and restrictive lung diseases?

Obstructive lung diseases involve difficulty with expiration, causing air trapping and elevated $\text{CO}_2$. Restrictive lung diseases involve difficulty with inspiration, leading to reduced compliance and impaired $\text{O}_2$ intake.

How is emphysema defined pathologically?

Permanent destruction of the respiratory unit / acinus distal to the terminal bronchioles, accompanied by loss of elastin and elastic recoil, and increased compliance.

What are the anatomical components of the respiratory unit / acinus?

The respiratory bronchioles, alveolar ducts, and alveoli (structures distal to the terminal bronchioles).

What are the two major forms of emphysema and their corresponding primary causes?

1. Centriacinar (central acinar) emphysema: caused primarily by cigarette smoking.
2. Panacinar emphysema: caused by $\alpha_1$-antitrypsin deficiency.

Why is a patient with emphysema referred to as a 'Pink Puffer'?

They maintain normal blood oxygen and carbon dioxide levels through pursed-lip breathing (which prolongs expiration to prevent collapse), but experience marked weight loss from the excessive work of respiratory muscle use.

What classic radiological findings are seen on chest X-ray in emphysema?

Hyperinflated lungs, flattened diaphragms, and a narrow/tubular heart.

What is the clinical definition of Chronic Bronchitis?

A chronic productive cough lasting for at least $> 3\,\text{months}$ over $2\,\text{consecutive years}$.

What is the hallmark histopathological change and post-mortem index in Chronic Bronchitis?

Hypertrophy and hyperplasia of submucosal mucus glands in the bronchi leading to mucus plugging. On post-mortem examination, the Reid Index is $> 40\%$.

How does Chronic Bronchitis lead to Cor Pulmonale ('Blue Bloaters')?

Mucus plugging causes retention of $\text{CO}_2$ and hypoxemia ($\downarrow \text{O}_2$), which induces hypoxic pulmonary vasoconstriction, leading to pulmonary hypertension, right ventricular hypertrophy, and eventually right heart failure (Cor Pulmonale) with cyanosis and peripheral edema/ascites.

What is the target oxygen saturation ($\text{SpO}_2$) range in a patient with COPD?

$$88\text{--}92\%$$

What underlying disease should be suspected in a young non-smoker presenting with emphysema and liver cirrhosis?

$\alpha_1$-antitrypsin deficiency.

What is bronchiectasis, and what is the diagnostic investigation of choice?

Bronchiectasis is the abnormal permanent dilatation of the bronchi. The investigation of choice (IOC) is High-Resolution Computed Tomography (HRCT); CXR classically shows a honeycomb or tram-track appearance.

What causes Kartagener syndrome (Primary Ciliary Dyskinesia), and how does it present?

It is caused by a congenital absence or defect of dynein arms in cilia. It presents with bronchiectasis, recurrent chest infections, male infertility, and situs inversus / dextrocardia.

What is the inheritance pattern, mutated gene, and channel defect in Cystic Fibrosis?

It is an autosomal recessive genetic disorder caused by mutations in the CFTR gene on chromosome 7, resulting in a defective chloride ($\text{Cl}^-$) channel.

What organism is the most common cause of pneumonia and respiratory death in patients with Cystic Fibrosis?

Pseudomonas aeruginosa.

What is the screening test versus the definitive diagnostic investigation of choice for Cystic Fibrosis?

Screening test: Sweat chloride test (shows elevated chloride). Investigation of choice (IOC): Genetic testing.

What immunological mechanism triggers allergic (atopic) asthma?

A Type I hypersensitivity reaction: allergen exposure triggers $\text{CD4}^+$ Th2 cells to stimulate B cells to produce IgE, which binds to mast cells. Re-exposure causes mast cell degranulation, releasing histamines and leukotrienes, accompanied by eosinophilic tissue infiltration.

What two microscopic structures are characteristic of asthma on sputum evaluation?

1. Curschmann spirals (shed bronchial epithelial casts)
2. Charcot-Leyden crystals (crystallized eosinophilic proteins)

What is the mechanism of aspirin-induced asthma, and what is its drug of choice?

Aspirin blocks cyclooxygenase (COX), shunting arachidonic acid metabolism to the lipoxygenase pathway and increasing bronchoconstrictive leukotrienes. The drug of choice is a leukotriene-receptor antagonist (LTRA, such as Montelukast or Zafirlukast).

Which anti-asthma medications cause oral candidiasis, muscle tremors, and seizures/arrhythmias, respectively?

Oral candidiasis (thrush): Inhaled corticosteroids (e.g., Fluticasone). Tremors and tachycardia: $\beta_2$-agonists (e.g., Salbutamol). Seizures/fits and arrhythmias: Phosphodiesterase inhibitors (e.g., Theophylline, Aminophylline).

What clinical criteria define acute severe asthma versus life-threatening asthma?

Acute severe asthma: Respiratory rate $> 25/\text{min}$, pulse rate $> 110/\text{bpm}$, and inability to complete sentences in one breath. Life-threatening asthma: Exhaustion, cyanosis, and a silent chest.

How do Pulmonary Function Tests (PFTs) differentiate obstructive from restrictive lung disease, and asthma from COPD?

Obstructive: $\text{FEV}_1 / \text{FVC} < 70\%$. Restrictive: $\text{FEV}_1 / \text{FVC}$ is normal or increased ($\ge 80\%$). Post-bronchodilator test (SABA for $15\,\text{min}$): Asthma improves by $> 12\%$, whereas COPD improves by $< 12\%$ or not at all.

How does Idiopathic Pulmonary Fibrosis (IPF) present clinically, and what is its definitive treatment?

Presents in older smokers ($> 55\,\text{years}$) with dry cough, progressive breathlessness, digital clubbing, and bilateral fine inspiratory crackles. It is irreversible; definitive treatment is lung transplantation.

What occupational exposure causes progressive massive fibrosis with black sputum containing black macrophages?

Coal Worker's Pneumoconiosis (caused by inhalation of carbon/anthracotic dust).

What occupational exposure presents with 'eggshell' hilar lymph node calcification and carries an increased risk of tuberculosis?

Silicosis (caused by silica dust inhalation in sandblasters and hard rock miners).

Which fibrotic lung diseases predominantly involve the upper lobes versus the lower lobes?

Upper lobe: Silicosis and Coal Worker's Pneumoconiosis. Lower lobe: Idiopathic Pulmonary Fibrosis, Asbestosis, and drug-induced fibrosis (Bleomycin, Amiodarone, Busulfan, Methotrexate, Carmustine, Cycloserine).

What conditions constitute Caplan Syndrome?

Occupational lung disease (pneumoconiosis) + Rheumatoid arthritis + Pulmonary nodules.

What is the histological hallmark of Sarcoidosis, and what laboratory abnormalities are seen?

Non-caseating granulomas with epithelioid histiocytes and multinucleated giant cells containing asteroid bodies. Labs show hypercalcemia (due to $\alpha_1$-hydroxylase activating vitamin D), elevated ACE ($\uparrow \text{ACE}$), and elevated ESR.

What triad characterizes Löfgren Syndrome in sarcoidosis?

Erythema nodosum (painful red nodules on shins) + Bilateral hilar lymphadenopathy + Arthralgia.

What environmental exposures cause Farmer's Lung, Bagassosis, and Byssinosis?

Farmer's Lung: Thermophilic actinomycetes in moldy hay. Bagassosis: Moldy sugarcane. Byssinosis: Cotton / textile dust.

How does Tension Pneumothorax present, and what is its emergency management?

Presents with severe dyspnea, bulging chest on the affected side, hyperresonance, decreased breath sounds, contralateral tracheal deviation, hypotension, and tachycardia. Immediate treatment is needle decompression at the $2\text{nd}$ intercostal space midclavicular line or $5\text{th}$ intercostal space midaxillary line.

According to Light's Criteria, what values define an exudative pleural effusion?

An effusion is exudative if:

1. $\frac{\text{Pleural fluid LDH}}{\text{Serum LDH}} > 0.6$, or
2. $\frac{\text{Pleural fluid protein}}{\text{Serum protein}} > 0.5$

What factors shift the oxygen-hemoglobin dissociation curve to the Right versus to the Left?

Right shift (unloads $\text{O}_2$ to tissues): Acidosis ($\uparrow \text{H}^+$), $\uparrow \text{CO}_2$, increased temperature, high altitude, and exercise. Left shift (holds $\text{O}_2$ tightly): Alkalosis, hypothermia, $\downarrow \text{CO}_2$, fetal hemoglobin ($\text{HbF}$), carbon monoxide (CO) poisoning, and methemoglobinemia.

What are the clinical findings, hypoxia types, and antidotes for Carbon Monoxide and Cyanide poisoning?

Carbon Monoxide: Early headache, cherry-red skin, anemic hypoxia; treated with $100\%\,\text{O}_2$. Cyanide: Bitter almond odor, histotoxic hypoxia; treated with Hydroxocobalamin (Vitamin $\text{B}_{12}$) or amyl nitrite.