USMLE Step 2 Quiz
Practice Pleural And Chest Wall Disorders in USMLE Step 2 with focused quiz questions that help you check what you know, review explanations, and build confidence with test-style prompts.
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A 20-year-old man presents with acute-onset severe shortness of breath and left-sided chest pain. He is anxious and tachypneic with a respiratory rate of 28/min. A chest x-ray shows a large left-sided pneumothorax with a 4 cm distance between the lung margin and the chest wall and a slight mediastinal shift to the right.
What is the most appropriate next step in management?
This quiz focuses on Pleural And Chest Wall Disorders, giving you a quick way to practice the rules, question types, and explanations that matter most for USMLE Step 2.
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A 20-year-old man presents with acute-onset severe shortness of breath and left-sided chest pain. He is anxious and tachypneic with a respiratory rate of 28/min. A chest x-ray shows a large left-sided pneumothorax with a 4 cm distance between the lung margin and the chest wall and a slight mediastinal shift to the right.
What is the most appropriate next step in management?
Explanation: A large (>3 cm) or symptomatic primary spontaneous pneumothorax requires intervention to re-expand the lung. The presence of significant symptoms (severe dyspnea, tachypnea) and the large size are clear indications for active intervention. The most definitive initial management is the insertion of a chest tube (thoracostomy). Needle aspiration is an alternative in some settings, but chest tube is the standard of care for a large, symptomatic pneumothorax.
A 72-year-old woman with a history of severe emphysema is brought to the emergency department with acute onset of severe dyspnea. Her oxygen saturation is 85% on room air. A chest x-ray confirms a large right-sided pneumothorax.
What is the most appropriate management for this patient?
Explanation: This patient has a secondary spontaneous pneumothorax, which occurs in the setting of underlying lung disease (emphysema). These are more dangerous than primary pneumothoraces because patients have limited pulmonary reserve. Therefore, all patients with secondary spontaneous pneumothorax, regardless of size, should be admitted to the hospital and managed with chest tube placement to ensure lung re-expansion and prevent recurrence.
A 65-year-old woman with an empyema has a chest tube placed. After 48 hours, her fevers persist, and drainage from the chest tube has decreased to less than 50 mL per day. A follow-up CT scan of the chest shows a persistent, large fluid collection with multiple internal septations (loculations).
What is the most appropriate next step in management?
Explanation: For a complicated, loculated pleural effusion or empyema that is not draining adequately with a chest tube alone, the next step is often to instill fibrinolytics (tissue plasminogen activator, tPA) and mucolytics (deoxyribonuclease, DNase) into the pleural space. This combination therapy helps to break down the fibrinous septations and viscous purulent material, facilitating drainage. If this fails, surgical intervention (VATS) is typically required.
A 45-year-old man with a history of chronic alcohol abuse is admitted with severe epigastric pain radiating to the back, nausea, and vomiting. His serum amylase and lipase are markedly elevated. Over the next two days, he develops shortness of breath. A chest x-ray reveals a left-sided pleural effusion.
Analysis of the pleural fluid is most likely to reveal a markedly elevated level of which of the following?
Explanation: The patient has acute pancreatitis, a common cause of pleural effusion, which is typically left-sided and exudative. Pancreatic enzymes can track into the pleural space, leading to a characteristically high pleural fluid amylase level (often higher than the serum level). High triglycerides suggest chylothorax, high adenosine deaminase suggests tuberculosis, and high creatinine suggests urinothorax.
A 65-year-old man with a long history of alcohol abuse and known cirrhosis is admitted for worsening abdominal distention and shortness of breath. Physical examination reveals scleral icterus, spider angiomata, shifting dullness in the abdomen, and absent breath sounds over the right lung base. A chest radiograph demonstrates a large right-sided pleural effusion.
What is the most likely mechanism underlying this patient's pleural effusion?
Explanation: This patient has hepatic hydrothorax, a complication of advanced cirrhosis with ascites. The mechanism involves the movement of ascitic fluid from the peritoneal cavity into the pleural space (most commonly the right side) through small defects in the diaphragm. The effusion is a transudate. While hypoalbuminemia contributes to fluid overload, the direct cause of the pleural effusion is this transdiaphragmatic passage.
A 72-year-old man with a history of hypertension, type 2 diabetes, and a myocardial infarction 5 years ago presents with a 2-week history of progressive shortness of breath and lower extremity swelling. He has orthopnea and paroxysmal nocturnal dyspnea. Physical exam reveals jugular venous distention, bibasilar crackles, and 2+ pitting edema to the mid-shins. A chest x-ray shows cardiomegaly and bilateral pleural effusions.
What is the most likely pathophysiologic mechanism responsible for this patient's pleural effusions?
Explanation: This patient's presentation is classic for decompensated congestive heart failure (CHF). In CHF, elevated left ventricular end-diastolic pressure leads to increased pressure in the pulmonary veins and capillaries. This increased hydrostatic pressure forces fluid out of the visceral pleural capillaries into the pleural space, resulting in a transudative pleural effusion.
A 58-year-old woman presents with a 5-day history of fever, chills, and a productive cough with yellow sputum. She also notes right-sided pleuritic chest pain. Physical exam reveals a temperature of 38.8°C (101.8°F), decreased breath sounds, and dullness to percussion over the right lower lung field. A chest x-ray confirms a right lower lobe infiltrate with a moderate-sized pleural effusion. Thoracentesis is performed.
Which of the following is the most likely finding in the pleural fluid, consistent with a parapneumonic effusion?
Explanation: The patient has pneumonia with a resultant parapneumonic effusion. Inflammation of the pleura leads to increased capillary permeability, causing leakage of protein and other large molecules into the pleural space. This results in an exudative effusion. According to Light's criteria, an exudate is defined by a pleural fluid/serum protein ratio > 0.5, a pleural fluid/serum LDH ratio > 0.6, or a pleural fluid LDH > 2/3 the upper limit of normal for serum LDH. The other options are characteristic of a transudative effusion.
A 40-year-old woman with a history of minimal change disease presents with significant peripheral edema, frothy urine, and dyspnea. Her laboratory results show serum albumin of 1.8 g/dL and 4+ protein on urinalysis. A chest X-ray reveals bilateral pleural effusions. A diagnostic thoracentesis is performed.
The pleural fluid is most likely to be characterized as which of the following?
Explanation: The patient has nephrotic syndrome, characterized by massive proteinuria leading to hypoalbuminemia and decreased plasma oncotic pressure. This systemic condition causes fluid to shift into the interstitial spaces, leading to generalized edema, including pleural effusions. Effusions caused by imbalances in hydrostatic or oncotic pressures, as seen here, are transudative.
A 62-year-old woman with a 20-year history of seropositive rheumatoid arthritis, which is poorly controlled, presents with progressive dyspnea and left-sided pleuritic chest pain. A chest x-ray shows a left-sided pleural effusion. Thoracentesis is performed.
Which set of pleural fluid findings is most consistent with this patient's underlying condition?
Explanation: Pleural effusions associated with rheumatoid arthritis are exudative and have a characteristic biochemical profile due to intense pleural inflammation and impaired glucose transport into the pleural space. This profile includes a very low glucose level (often <30 mg/dL), a low pH (<7.20), and a very high LDH level. The other options describe transudative effusions or effusions more typical of other conditions like tuberculosis.
A 55-year-old man with a history of smoking presents with a 3-month history of weight loss, cough, and dyspnea. A chest x-ray reveals a large left-sided pleural effusion. Thoracentesis is performed. Pleural fluid analysis shows: protein 4.5 g/dL, LDH 400 U/L. Serum analysis shows: protein 7.0 g/dL, LDH 250 U/L. The upper limit of normal for serum LDH is 200 U/L.
How should this pleural effusion be classified according to Light's criteria?
Explanation: This effusion is exudative. Light's criteria are met if any of the following are true: 1) Pleural fluid protein/serum protein ratio > 0.5 (4.5/7.0 = 0.64); 2) Pleural fluid LDH/serum LDH ratio > 0.6 (400/250 = 1.6); 3) Pleural fluid LDH > 2/3 the upper limit of normal for serum LDH (400 > 2/3 * 200 ≈ 133). This fluid meets all three criteria, confirming it is an exudate, likely due to malignancy in this clinical context.
A 34-year-old man who recently emigrated from Southeast Asia presents with a 6-week history of low-grade fever, night sweats, weight loss, and a nonproductive cough. Chest x-ray shows a right-sided pleural effusion. Thoracentesis is performed, and the fluid is serous and straw-colored. Analysis reveals a protein level of 4.8 g/dL, LDH of 350 U/L, and a white blood cell count of 1200/μL with 90% lymphocytes.
What is the most likely diagnosis?
Explanation: The clinical presentation (subacute constitutional symptoms, endemic area) combined with an exudative, lymphocytic-predominant pleural effusion is classic for tuberculous pleurisy. Malignancy can also cause a similar fluid profile but is less likely given the patient's age and specific symptoms. Acute bacterial pneumonia causes a neutrophilic effusion, and congestive heart failure causes a transudative effusion.
A 60-year-old woman who recently underwent a total knee replacement develops acute onset of dyspnea and pleuritic chest pain. A CT angiogram of the chest confirms a pulmonary embolism. She is also found to have a small right-sided pleural effusion.
If thoracentesis were performed, which of the following findings would be most characteristic?
Explanation: Pleural effusions secondary to pulmonary embolism (PE) are typically exudative (in about 80% of cases) due to ischemia and inflammation of the pleura. Therefore, the fluid would be expected to meet at least one of Light's criteria for an exudate, such as an elevated LDH level. The effusion is usually small and may be bloody, but the other options are not characteristic. A protein ratio <0.5 suggests a transudate, purulent fluid suggests empyema, and a pH <7.20 suggests a complicated parapneumonic effusion.
A 22-year-old tall, thin man with no significant medical history presents to the emergency department with the sudden onset of sharp, right-sided chest pain and shortness of breath. This began 2 hours ago while he was resting. He smokes one pack of cigarettes per day. His vital signs are stable. On examination, breath sounds are diminished on the right side.
What is the most likely diagnosis?
Explanation: This is the classic presentation of a primary spontaneous pneumothorax, which occurs without underlying lung disease. It is most common in tall, thin young men, and smoking is a major risk factor. The cause is the rupture of a subpleural apical bleb. The acute onset of unilateral pleuritic chest pain and dyspnea with diminished breath sounds on the affected side is highly suggestive.
A 68-year-old man with a 40-pack-year smoking history and severe COPD presents with a sudden worsening of his chronic dyspnea. He appears in moderate respiratory distress. Physical examination reveals hyperresonance to percussion and absent breath sounds over the left hemithorax. His oxygen saturation is 86% on 2 L of nasal cannula.
What is the most likely cause of his acute decompensation?
Explanation: Sudden clinical deterioration in a patient with known underlying lung disease like COPD should raise suspicion for a secondary spontaneous pneumothorax. This occurs due to the rupture of an underlying bleb or bulla. The unilateral physical findings of hyperresonance and absent breath sounds are classic for pneumothorax. While this is technically a type of COPD exacerbation, 'secondary spontaneous pneumothorax' is the more specific and actionable diagnosis.
A 25-year-old man is brought to the emergency department after a motor vehicle collision. He is agitated, tachycardic at 140/min, and hypotensive at 80/50 mmHg. He has significant bruising over the right side of his chest. On physical examination, his trachea is deviated to the left, he has marked jugular venous distention, and breath sounds are absent on the right side.
What is the most appropriate immediate next step in management?
Explanation: This patient has the classic signs of a tension pneumothorax: hypotension (obstructive shock), tachycardia, jugular venous distention, tracheal deviation away from the affected side, and absent breath sounds. This is a clinical diagnosis and a life-threatening emergency. Immediate needle decompression in the second intercostal space at the midclavicular line is required to convert the tension pneumothorax to a simple pneumothorax, followed by chest tube placement. Waiting for an x-ray would be a fatal delay.
A 24-year-old healthy man presents with mild right-sided pleuritic chest pain. A chest x-ray reveals a small right-sided pneumothorax, with the pleural line 1.5 cm from the chest wall at the apex. His vital signs are stable, and he is in no respiratory distress.
What is the most appropriate management?
Explanation: For a small (<2-3 cm) primary spontaneous pneumothorax in a clinically stable and asymptomatic or minimally symptomatic patient, conservative management is recommended. This involves observation and administration of supplemental oxygen. Oxygen increases the pressure gradient for nitrogen in the pleural space, accelerating the rate of pneumothorax resorption.
A 56-year-old man with diabetes is being treated for community-acquired pneumonia with appropriate antibiotics. After 5 days of therapy, he remains febrile to 39.0°C (102.2°F) and continues to have pleuritic chest pain. A repeat chest x-ray shows an increase in the size of the parapneumonic effusion, which now appears loculated on a lateral decubitus film.
What is the most likely diagnosis?
Explanation: Persistent fever despite appropriate antibiotic therapy for pneumonia, coupled with a worsening and loculated pleural effusion, is highly suggestive of the development of a complicated parapneumonic effusion or empyema. An empyema is a collection of pus in the pleural space that requires drainage for source control and resolution of the infection. A lung abscess is an infection within the lung parenchyma, while PE and drug resistance are less likely to cause a loculated effusion.
A 60-year-old woman is hospitalized with right-sided pneumonia. Due to persistent fevers, a thoracentesis is performed on a moderate-sized pleural effusion. The fluid aspirated is thick and purulent. Gram stain of the fluid reveals gram-positive cocci in chains.
In addition to continuing appropriate systemic antibiotics, what is the most important next step in management?
Explanation: The presence of grossly purulent fluid (pus) or a positive Gram stain from the pleural space defines an empyema. This is an absolute indication for complete drainage of the infected fluid. The standard initial procedure for achieving this is the placement of a chest tube (tube thoracostomy). Antibiotics alone are insufficient, and incomplete drainage leads to poor outcomes.
A 48-year-old man with pneumonia has a pleural effusion. Thoracentesis is performed. The pleural fluid is a yellow, cloudy fluid that is not grossly purulent. The Gram stain is negative. Analysis shows: pH 7.10, glucose 45 mg/dL, LDH 1200 U/L.
Which of the following is the most appropriate next step?
Explanation: This patient has a complicated parapneumonic effusion. Even without a positive Gram stain or purulence, a pleural fluid pH < 7.20 or a glucose level < 60 mg/dL indicates a high level of inflammation and bacterial activity that will not resolve with antibiotics alone. These findings are indications for complete drainage of the pleural space, typically via a chest tube, to prevent the formation of a fibrous peel and trapped lung.
An 80-year-old nursing home resident with poor dentition and a history of a stroke with dysphagia aspirated and developed pneumonia. He subsequently developed an empyema. A sample of the pleural fluid is sent for culture.
Which type of organism is most likely to be isolated from the pleural fluid?
Explanation: Empyemas that develop in the context of aspiration pneumonia are typically polymicrobial. The source of the infection is the oropharynx. In a patient with risk factors like poor dentition and dysphagia, the inoculum is likely to contain a mix of aerobic and anaerobic bacteria (e.g., Peptostreptococcus, Bacteroides, Fusobacterium). The other options are atypical pathogens or viruses that are uncommon causes of empyema.