Restrictive lung disease mechanics US Medical PG Practice Questions and MCQs
Practice US Medical PG questions for Restrictive lung disease mechanics. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
Restrictive lung disease mechanics US Medical PG Question 1: A 60-year-old woman with a history of emphysema has been referred by her pulmonologist for follow-up pulmonary function testing. During the test, the patient reaches a point where her airway pressure is equal to the atmospheric pressure. Which of the following is most likely to be found during this respiratory state?
- A. Pulmonary vascular resistance is at a maximum
- B. Transmural pressure of the lung-chest wall system is at a maximum
- C. Transmural pressure of the chest wall is at a minimum
- D. Pulmonary vascular resistance is at a minimum (Correct Answer)
- E. Transmural pressure of the lung-chest wall system is at a minimum
Restrictive lung disease mechanics Explanation: ***Pulmonary vascular resistance is at a minimum***
- When airway pressure equals atmospheric pressure during a pulmonary function test, the lungs are at **functional residual capacity (FRC)** or resting state.
- At FRC, **pulmonary vascular resistance (PVR)** is at its lowest point due to the optimal balance between alveolar and extra-alveolar vessel compression/distension.
- Extra-alveolar vessels are compressed at low lung volumes, while alveolar vessels are compressed at high lung volumes. At FRC, both are optimally distended, resulting in **minimal PVR**.
*Pulmonary vascular resistance is at a maximum*
- PVR increases at very low lung volumes (due to extra-alveolar vessel compression) and very high lung volumes (due to alveolar vessel compression).
- The resting state (airway pressure equals atmospheric pressure) corresponds to FRC, where PVR is **minimal, not maximal**.
*Transmural pressure of the lung-chest wall system is at a maximum*
- Transmural pressure of the lung-chest wall system represents the pressure difference across the entire respiratory system.
- This pressure is higher during inspiration or forced expiration when the system is stretched or compressed.
- At FRC (airway pressure equals atmospheric pressure), the system is at **resting equilibrium**, not at maximal transmural pressure.
*Transmural pressure of the chest wall is at a minimum*
- Transmural pressure across the chest wall is the difference between intrapleural pressure and atmospheric pressure.
- This pressure is not at a minimum when airway pressure equals atmospheric pressure.
- Chest wall transmural pressure is actually minimal near **residual volume (RV)**, where the chest wall recoils inward most strongly.
*Transmural pressure of the lung-chest wall system is at a minimum*
- Transmural pressure of the lung-chest wall system reflects the elastic recoil forces of the combined system.
- At FRC (airway pressure equals atmospheric pressure), elastic recoil forces are balanced at equilibrium, but transmural pressure is **not at a minimum**—it represents the neutral resting state.
Restrictive lung disease mechanics US Medical PG Question 2: Which of the following physiologic changes decreases pulmonary vascular resistance (PVR)?
- A. Inhaling the inspiratory reserve volume (IRV)
- B. Exhaling the entire vital capacity (VC)
- C. Exhaling the expiratory reserve volume (ERV)
- D. Breath holding maneuver at functional residual capacity (FRC)
- E. Inhaling the entire vital capacity (VC) (Correct Answer)
Restrictive lung disease mechanics Explanation: ***Inhaling the entire vital capacity (VC)***
- As lung volume increases from FRC to TLC (which includes inhaling the entire VC), alveolar vessels are **stretched open**, and extra-alveolar vessels are **pulled open** by the increased radial traction, leading to a decrease in PVR.
- This **maximizes the cross-sectional area** of the pulmonary vascular bed, lowering resistance.
*Inhaling the inspiratory reserve volume (IRV)*
- While inhaling IRV increases lung volume, it's not the maximal inspiration of the entire VC where **PVR is typically at its lowest**.
- PVR continues to decrease as lung volume approaches total lung capacity (TLC).
*Exhaling the entire vital capacity (VC)*
- Exhaling the entire vital capacity leads to very low lung volumes, where PVR significantly **increases**.
- At low lung volumes, **alveolar vessels become compressed** and extra-alveolar vessels **narrow**, increasing resistance.
*Exhaling the expiratory reserve volume (ERV)*
- Exhaling the ERV results in a lung volume below FRC, which causes a **marked increase in PVR**.
- This is due to the **compression of alveolar vessels** and decreased radial traction on extra-alveolar vessels.
*Breath holding maneuver at functional residual capacity (FRC)*
- At FRC, the PVR is at an **intermediate level**, not its lowest.
- This is the point where the opposing forces affecting alveolar and extra-alveolar vessels are somewhat balanced, but not optimized for minimal resistance.
Restrictive lung disease mechanics US Medical PG Question 3: A 65-year-old male presents to your office complaining of worsening shortness of breath. He has experienced shortness of breath on and off for several years, but is noticing that it is increasingly more difficult. Upon examination, you note wheezing and cyanosis. You conduct pulmonary function tests, and find that the patient's FEV1/FVC ratio is markedly decreased. What is the most likely additional finding in this patient?
- A. Decreased serum bicarbonate
- B. Increased IgE
- C. Increased erythropoietin (Correct Answer)
- D. Pleural effusion
- E. Nasal polyps
Restrictive lung disease mechanics Explanation: **Increased erythropoietin**
- The patient's presentation of worsening **shortness of breath**, **wheezing**, and **cyanosis**, along with a **markedly decreased FEV1/FVC ratio**, indicates a severe **obstructive lung disease**, likely **COPD**.
- **Chronic hypoxemia** (due to impaired gas exchange in severe obstructive lung disease) stimulates the kidneys to produce more **erythropoietin**, leading to secondary **polycythemia** to increase oxygen-carrying capacity.
*Decreased serum bicarbonate*
- **Decreased serum bicarbonate** typically indicates **metabolic acidosis**, which is not a primary or direct consequence of chronic obstructive lung disease.
- In chronic respiratory conditions, the body often compensates for **respiratory acidosis** by **increasing bicarbonate retention**, leading to a normal or increased bicarbonate level.
*Increased IgE*
- **Elevated IgE** levels are characteristic of **atopic conditions** like **asthma** or allergic reactions, which are not explicitly suggested as the primary issue in this patient's chronic and progressive symptoms.
- While asthma can have an obstructive pattern, the description of chronic worsening symptoms and cyanosis points more towards **COPD**, where IgE is not typically a direct distinguishing factor.
*Pleural effusion*
- **Pleural effusion** is an accumulation of fluid in the pleural space and would typically present with **dullness to percussion** and **decreased breath sounds** over the affected area, not primarily wheezing.
- While some lung conditions can be complicated by pleural effusion, it is not a direct or most likely additional finding based on the presented symptoms of obstructive lung disease.
*Nasal polyps*
- **Nasal polyps** are benign growths in the nasal passages and are often associated with conditions like **aspirin-exacerbated respiratory disease** or **chronic rhinosinusitis**.
- They are not a direct or common additional finding in the context of the severe and chronic obstructive lung disease described with systemic hypoxemia.
Restrictive lung disease mechanics US Medical PG Question 4: A 57-year-old man comes to the physician because of a 2-year history of fatigue, worsening shortness of breath, and a productive cough for 2 years. He has smoked 1 pack of cigarettes daily for the past 40 years. Examination shows pursed-lip breathing and an increased anteroposterior chest diameter. There is diffuse wheezing bilaterally and breath sounds are distant. Which of the following parameters is most likely to be decreased in this patient?
- A. Thickness of small airways
- B. Work of breathing
- C. Lung elastic recoil (Correct Answer)
- D. Lower airway resistance
- E. Pulmonary vascular pressure
Restrictive lung disease mechanics Explanation: ***Lung elastic recoil***
- The patient's presentation (long smoking history, dyspnea, pursed-lip breathing, increased AP diameter, distant breath sounds, and wheezing) is classic for **emphysema**, a form of **COPD**.
- Emphysema involves the destruction of **alveolar walls** and **elastic fibers**, leading to a significant decrease in the lung's ability to passively recoil during expiration.
*Thickness of small airways*
- In COPD, particularly chronic bronchitis, there is often **inflammation and thickening of the small airways** due to goblet cell hyperplasia and mucus gland hypertrophy, increasing their thickness, not decreasing it.
- This thickening contributes to increased airway resistance.
*Work of breathing*
- The **destruction of elastic recoil** in emphysema means the patient must actively use accessory muscles to exhale, significantly **increasing the work of breathing**, which is evident from pursed-lip breathing.
- Patients with COPD expend much more energy to breathe than healthy individuals.
*Lower airway resistance*
- Emphysema, while characterized by alveolar destruction, also has an obstructive component due to **airway collapse during expiration** (loss of radial traction) and potential inflammation/mucus, which leads to **increased lower airway resistance**, not decreased resistance.
- This increased resistance contributes to air trapping and wheezing.
*Pulmonary vascular pressure*
- Chronic hypoxia resulting from severe COPD can lead to **pulmonary vasoconstriction** and remodeling of the pulmonary arteries, causing **pulmonary hypertension** and an increase in pulmonary vascular pressure.
- This is a common complication in advanced COPD, not a decreased parameter.
Restrictive lung disease mechanics US Medical PG Question 5: A 72-year-old obese man presents as a new patient to his primary care physician because he has been feeling tired and short of breath after recently moving to Denver. He is a former 50 pack-year smoker and has previously had deep venous thrombosis. Furthermore, he previously had a lobe of the lung removed due to lung cancer. Finally, he has a family history of a progressive restrictive lung disease. Laboratory values are obtained as follows:
Oxygen tension in inspired air = 130 mmHg
Alveolar carbon dioxide tension = 48 mmHg
Arterial oxygen tension = 58 mmHg
Respiratory exchange ratio = 0.80
Respiratory rate = 20/min
Tidal volume = 500 mL
Which of the following mechanisms is consistent with these values?
- A. Shunt physiology
- B. High altitude
- C. V/Q mismatch
- D. Pulmonary fibrosis
- E. Hypoventilation (Correct Answer)
Restrictive lung disease mechanics Explanation: ***Hypoventilation***
- The arterial oxygen tension (PaO2) of 58 mmHg is consistent with hypoxemia, and the alveolar carbon dioxide tension (PACO2) of 48 mmHg (normal 35-45 mmHg) indicates **hypercapnia**, a hallmark of hypoventilation.
- The **alveolar-arterial (A-a) gradient** can be calculated using the alveolar gas equation: PAO2 = PiO2 - PACO2/R. Here, PAO2 = 130 mmHg - 48 mmHg/0.8 = 130 - 60 = 70 mmHg. The A-a gradient is PAO2 - PaO2 = 70 - 58 = 12 mmHg, which is within the normal range (5-15 mmHg), indicating that the hypoxemia is primarily due to **decreased alveolar ventilation**.
*Shunt physiology*
- A shunt would cause a significant reduction in PaO2 and a **widened A-a gradient** (typically >15 mmHg) due to deoxygenated blood bypassing ventilated areas.
- While shunts do not typically cause hypercapnia unless very severe, the normal A-a gradient here rules out a significant shunt as the primary mechanism for hypoxemia.
*High altitude*
- Moving to a high altitude (like Denver) causes a decrease in **inspired oxygen tension (PiO2)**, leading to hypoxemia.
- However, the provided inspired oxygen tension (130 mmHg) is above what would be expected for significant high-altitude hypoxemia at sea level equivalent, and the hypoxemia here is associated with hypercapnia, which is not a direct result of high altitude itself.
*V/Q mismatch*
- A V/Q mismatch leads to hypoxemia and a **widened A-a gradient**, as some areas of the lung are either underventilated or underperfused.
- While it can cause hypoxemia, a V/Q mismatch is typically associated with **normal or low PaCO2** due to compensatory hyperventilation, not hypercapnia, and the A-a gradient would be elevated.
*Pulmonary fibrosis*
- Pulmonary fibrosis is a restrictive lung disease that leads to impaired gas exchange, causing hypoxemia primarily due to **V/Q mismatch** and **diffusion limitation**.
- This would result in a **widened A-a gradient** and often a **low PaCO2** due to compensatory hyperventilation, rather than the elevated PaCO2 observed in this patient.
Restrictive lung disease mechanics US Medical PG Question 6: A 22-year-old woman presents to the emergency department with a chief concern of shortness of breath. She was hiking when she suddenly felt unable to breathe and had to take slow deep breaths to improve her symptoms. The patient is a Swedish foreign exchange student and does not speak any English. Her past medical history and current medications are unknown. Her temperature is 99.5°F (37.5°C), blood pressure is 127/68 mmHg, pulse is 120/min, respirations are 22/min, and oxygen saturation is 90% on room air. Physical exam is notable for poor air movement bilaterally and tachycardia. The patient is started on treatment. Which of the following best describes this patient's underlying pathology?
FEV1 = Forced expiratory volume in 1 second
FVC = Forced vital capacity
DLCO = Diffusing capacity of carbon monoxide
- A. Increased FVC
- B. Increased FEV1
- C. Increased FEV1/FVC
- D. Decreased airway tone
- E. Normal DLCO (Correct Answer)
Restrictive lung disease mechanics Explanation: ***Normal DLCO***
- This patient presents with an acute exacerbation of what is likely **asthma**, showing symptoms of **shortness of breath**, **tachycardia**, poor air movement bilaterally, and improvement with slow deep breaths. **Asthma** characteristically affects the airways and not the alveoli, thus the **diffusing capacity of carbon monoxide (DLCO)**, which measures gas exchange across the alveolar-capillary membrane, would be expected to be normal.
- In asthma, the primary problem is **bronchoconstriction** and **airway inflammation**, which restricts airflow but does not typically impair the diffusion of gases like carbon monoxide across the alveolar-capillary membrane.
*Increased FVC*
- **Forced vital capacity (FVC)** is often normal or even slightly reduced in asthma due to **air trapping** and early airway closure, not increased.
- An increased FVC is usually not associated with obstructive lung diseases like asthma but could potentially be seen in conditions where lung volumes are pathologically large, which is not the case here.
*Increased FEV1*
- **Forced expiratory volume in 1 second (FEV1)** is typically **decreased** in obstructive lung diseases like asthma due to **airflow limitation**.
- An increased FEV1 would indicate better-than-average expiratory flow, which contradicts the symptoms of shortness of breath and poor air movement in this patient.
*Increased FEV1/FVC*
- The **FEV1/FVC ratio** is characteristically **decreased** in obstructive lung diseases like asthma, indicating that a disproportionately smaller amount of air can be exhaled in the first second relative to the total forced vital capacity.
- An increased FEV1/FVC ratio would be a sign of a restrictive lung disease or normal lung function, not an exacerbation of an obstructive process.
*Decreased airway tone*
- The underlying pathology in asthma is typically **bronchoconstriction**, which means an **increased airway tone** and narrowing of the airways, rather than decreased.
- Decreased airway tone would imply bronchodilation, which would alleviate, not cause, the patient's symptoms of shortness of breath and poor air movement.
Restrictive lung disease mechanics US Medical PG Question 7: A 60-year-old man presents with breathlessness for the past 3 months. His symptoms have been getting progressively worse during this time. He denies any history of cough, fever, or chest pain. He works at a local shipyard and is responsible for installing the plumbing aboard the vessels. His past medical history is significant for hypertension for which he takes metoprolol every day. He denies smoking and any illicit drug use. His pulse is 74/min, respiratory rate is 14/min, blood pressure is 130/76 mm Hg, and temperature is 36.8°C (98.2°F). Physical examination is significant for fine bibasilar crackles at the end of inspiration without digital clubbing. Which of the following additional findings would most likely be present in this patient?
- A. Increased pulmonary capillary wedge pressure
- B. Increased residual lung volume
- C. Reduced FEV1/FVC ratio
- D. Decreased diffusing capacity of CO (Correct Answer)
- E. Decreased pulmonary arterial pressure
Restrictive lung disease mechanics Explanation: ***Decreased diffusing capacity of CO***
- This patient's occupation at a **shipyard**, progressive dyspnea, and bibasilar crackles without clubbing, along with normal vital signs, are highly suggestive of **asbestosis**, a type of **interstitial lung disease (ILD)**.
- ILDs cause **fibrosis of the alveolar-capillary membrane**, leading to impaired gas exchange and a characteristic **reduction in DLCO (diffusing capacity of the lung for carbon monoxide)**. This is a hallmark of parenchymal lung disease.
*Increased pulmonary capillary wedge pressure*
- An elevated **pulmonary capillary wedge pressure (PCWP)** indicates **left-sided heart failure** or **pulmonary venous hypertension**.
- While dyspnea can be a symptom of heart failure, the patient's normal blood pressure and absence of cardiac-specific symptoms or signs point away from primary cardiac pathology.
*Increased residual lung volume*
- **Increased residual lung volume** is a characteristic finding in **obstructive lung diseases** such as **COPD** and **asthma**, where there is air trapping due to airflow limitation.
- The patient's presentation with progressive dyspnea and bibasilar crackles is more consistent with a **restrictive lung disorder** like asbestosis, which typically causes **decreased lung volumes**.
*Reduced FEV1/FVC ratio*
- A **reduced FEV1/FVC ratio** is the hallmark of **obstructive lung diseases**, indicating airflow limitation.
- In **restrictive lung diseases** like asbestosis, both FEV1 and FVC are typically reduced proportionally, often resulting in a **normal or even increased FEV1/FVC ratio**.
*Decreased pulmonary arterial pressure*
- **Pulmonary arterial pressure (PAP)** is typically **normal or increased** in patients with interstitial lung disease due to **hypoxic vasoconstriction** and vascular remodeling.
- A decreased PAP would be an unusual and atypical finding in such a patient and is not associated with this clinical picture.
Restrictive lung disease mechanics US Medical PG Question 8: A 49-year-old woman comes to the physician because of a 4-month history of a dry cough and shortness of breath on exertion. She also reports recurrent episodes of pain, stiffness, and swelling in her wrist and her left knee over the past 6 months. She had two miscarriages at age 24 and 28. Physical examination shows pallor, ulcerations on the palate, and annular hyperpigmented plaques on the arms and neck. Fine inspiratory crackles are heard over bilateral lower lung fields on auscultation. Which of the following additional findings is most likely in this patient?
- A. Increased airway resistance
- B. Decreased A-a gradient
- C. Decreased right atrial pressure
- D. Decreased diffusing capacity (Correct Answer)
- E. Increased lung compliance
Restrictive lung disease mechanics Explanation: ***Decreased diffusing capacity***
- This patient presents with symptoms highly suggestive of **systemic lupus erythematosus (SLE)**, including recurrent miscarriages, joint pain, oral ulcers, skin lesions (annular hyperpigmented plaques), and pulmonary involvement (dry cough, dyspnea, crackles).
- **Interstitial lung disease (ILD)**, a common pulmonary manifestation of SLE, leads to **fibrosis** of the alveolar-capillary membrane, thereby **decreasing the diffusing capacity of the lung for carbon monoxide (DLCO)**.
*Increased airway resistance*
- Increased airway resistance is characteristic of **obstructive lung diseases** like asthma or COPD, which primarily involve narrowing of the airways.
- The patient's presentation with **inspiratory crackles** and symptoms of restrictive disease (shortness of breath on exertion, dry cough) is not consistent with increased airway resistance.
*Decreased A-a gradient*
- A **decreased alveolar-arterial (A-a) gradient** indicates efficient gas exchange and is typically seen in healthy individuals or in conditions causing hypoventilation without intrinsic lung disease.
- In conditions like pulmonary fibrosis or ILD, there is impaired gas exchange leading to an **increased A-a gradient**.
*Decreased right atrial pressure*
- **Decreased right atrial pressure** would typically signify reduced venous return or normal cardiac function.
- Given the patient's respiratory symptoms and potential for pulmonary hypertension secondary to ILD, an **increased right atrial pressure** would be more likely due to increased pulmonary vascular resistance.
*Increased lung compliance*
- **Increased lung compliance** is seen in conditions where the lung tissue becomes more distensible, such as **emphysema**, due to destruction of elastic fibers.
- **Interstitial lung disease** and pulmonary fibrosis, as suggested by the patient's symptoms and signs, lead to **decreased lung compliance** due to stiffening of the lung tissue.
Restrictive lung disease mechanics US Medical PG Question 9: A 37-year-old woman comes to the physician because of a 10-month history of excessive daytime sleepiness and fatigue. She says she has difficulty concentrating and has fallen asleep at work on numerous occasions. She also reports having frequent headaches during the day. She has no difficulty falling asleep at night, but wakes up gasping for breath at least once. She has always snored loudly and began using an oral device to decrease her snoring a year ago. She has occasional lower back pain, for which she takes tramadol tablets 1–2 times per week. She also began taking one rabeprazole tablet daily 3 weeks ago. She does not smoke. She is 175 cm (5 ft 7 in) tall and weighs 119 kg (262 lb); BMI is 38.8 kg/m2. Her vital signs are within normal limits. Physical and neurologic examinations show no other abnormalities. Arterial blood gas analysis on room air shows:
pH 7.35
PCO2 51 mm Hg
PO2 64 mm Hg
HCO3- 29 mEq/L
O2 saturation 92%
An x-ray of the chest and ECG show no abnormalities. Which of the following is the most likely cause of this patient's condition?
- A. Chronic inflammatory airflow limitation
- B. Thickening of alveolar membranes
- C. Drug-induced respiratory depression
- D. Diurnal alveolar hypoventilation
- E. Apneic episodes with obstructed upper airways (Correct Answer)
Restrictive lung disease mechanics Explanation: **Apneic episodes with obstructed upper airways**
- This patient has classic **obstructive sleep apnea (OSA)**, characterized by **loud snoring**, **waking up gasping for breath** (witnessed apneas), and **excessive daytime sleepiness**.
- Her **obesity (BMI 38.8)** is a major risk factor for OSA, as excess soft tissue in the upper airway predisposes to collapse during sleep.
- The ABG shows **compensated respiratory acidosis (pH 7.35, PCO2 51, HCO3- 29)** and **hypoxemia (PO2 64, O2 sat 92%)**, indicating chronic hypoventilation from recurrent apneic episodes.
- OSA is the **underlying cause** of her condition; the oral device she uses is typically employed to treat OSA by repositioning the jaw to maintain airway patency.
- The question asks for the **cause** of her condition, which is the **obstructed upper airways** leading to apneic episodes during sleep.
*Diurnal alveolar hypoventilation*
- While this patient does have daytime (diurnal) hypoventilation as evidenced by the elevated PCO2, this is a **consequence** of severe OSA, not the primary cause.
- This describes **Obesity Hypoventilation Syndrome (OHS)**, which overlaps with OSA but refers specifically to the chronic hypoventilation state.
- The **obstructed airways causing apneic episodes** are the underlying pathophysiology that leads to the chronic hypoventilation.
*Chronic inflammatory airflow limitation*
- This refers to **COPD**, which typically presents with **dyspnea, chronic cough, and wheezing**.
- The patient is a **non-smoker**, has a **normal chest x-ray**, and lacks respiratory symptoms typical of COPD.
- The clinical picture is classic for OSA, not obstructive lung disease.
*Thickening of alveolar membranes*
- This describes **interstitial lung diseases (ILD)**, which present with **progressive dyspnea, restrictive physiology**, and often **interstitial infiltrates on imaging**.
- The patient's **normal chest x-ray** and lack of exertional dyspnea make ILD unlikely.
- Her symptoms are related to sleep-disordered breathing, not parenchymal lung disease.
*Drug-induced respiratory depression*
- **Tramadol** (an opioid) can cause respiratory depression, but she takes it only **1-2 times per week** for back pain.
- The ABG shows **compensated** respiratory acidosis with elevated bicarbonate, indicating a **chronic process** lasting weeks to months, not acute drug effect.
- Her symptoms (snoring, gasping, daytime sleepiness) and obesity clearly point to OSA as the cause.
Restrictive lung disease mechanics US Medical PG Question 10: A 57-year-old man is brought to the emergency department by his wife 20 minutes after having had a seizure. He has had recurrent headaches and dizziness for the past 2 weeks. An MRI of the brain shows multiple, round, well-demarcated lesions in the brain parenchyma at the junction between gray and white matter. This patient's brain lesions are most likely comprised of cells that originate from which of the following organs?
- A. Kidney
- B. Skin
- C. Lung (Correct Answer)
- D. Thyroid
- E. Prostate
Restrictive lung disease mechanics Explanation: ***Lung (Correct Answer)***
- **Lung cancer** is the most common cause of **brain metastases** in adults, accounting for approximately **50% of all cases**
- The clinical presentation—seizure, headaches, dizziness, and **multiple, round, well-demarcated lesions at the gray-white matter junction**—is classic for metastatic lung cancer
- Both **small cell and non-small cell lung cancers** have high propensity for hematogenous spread to the brain
- The watershed areas at the gray-white junction are common sites due to lodging of tumor emboli in terminal arterioles
*Kidney (Incorrect)*
- **Renal cell carcinoma (RCC)** can metastasize to the brain but accounts for only **5-10% of brain metastases**
- While RCC metastases can appear similar on imaging, lung cancer is statistically more likely given its higher prevalence
- RCC metastases are often **highly vascular and may hemorrhage**, which is not mentioned in this case
*Skin (Incorrect)*
- **Melanoma** has the **highest propensity per case** to metastasize to the brain among all cancers
- However, the **overall incidence of melanoma is much lower** than lung cancer, making it a less probable primary source
- Melanoma brain metastases often present as **hemorrhagic lesions** and would typically have skin findings or history
*Thyroid (Incorrect)*
- **Thyroid cancer** rarely metastasizes to the brain (accounts for <1% of brain metastases)
- Brain metastases from thyroid cancer typically occur in **advanced papillary or follicular carcinoma** or in **anaplastic thyroid cancer**
- More common metastatic sites for thyroid cancer are lung and bone
*Prostate (Incorrect)*
- **Prostate cancer very rarely metastasizes to the brain** (<1% of cases)
- Prostate cancer preferentially metastasizes to **bone (especially axial skeleton), lymph nodes, and liver**
- Brain metastases from prostate cancer suggest extremely advanced, aggressive disease and are exceptionally uncommon
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