What is the most likely diagnosis for a patient presenting with acute onset of dyspnea (shortness of breath), hemoptysis (coughing up blood), and sharp stabbing chest pain that worsens with inspiration, alongside tachypnea (elevated respiratory rate)?

Pulmonary Embolism (D)

The most likely diagnosis is pulmonary embolism (D), given the classic triad of acute dyspnea with tachypnea, hemoptysis, and pleuritic chest pain in an obese patient with significant risk factors.

Clinical Reasoning

This patient presents with the hallmark features of the "pulmonary hemorrhage syndrome" pattern of PE, which includes:

• Pleuritic chest pain (sharp, stabbing, worse on inspiration) - present in 52% of PE cases, caused by pleural irritation from distal emboli 1, 2
• Hemoptysis - present in 11% of PE cases, resulting from alveolar hemorrhage caused by small distal emboli 1, 2
• Acute dyspnea with marked tachypnea (32 breaths/min) - dyspnea occurs in 80% of PE cases, and tachypnea (>20/min) is present in 70% 1, 2
• Obesity - a recognized risk factor for venous thromboembolism 1

Why Not the Other Diagnoses?

Dissecting Aneurysm (A) - Unlikely

• Typically presents with sudden, severe, tearing chest pain radiating to the back, not pleuritic pain 1
• Hemoptysis is not a characteristic feature of aortic dissection 1
• The pleuritic nature of the pain (worse with inspiration) points away from this diagnosis 1

Pneumothorax (B) - Unlikely

• While pneumothorax can cause acute dyspnea and pleuritic chest pain, hemoptysis is not a feature 1
• The combination of hemoptysis with pleuritic pain is more consistent with PE 1, 2

Lobar Pneumonia (C) - Less Likely

• Pneumonia typically presents with productive cough, fever (>38.5°C), and purulent sputum 1, 2
• Fever is present in only 7% of PE cases but is common in pneumonia 1, 2
• The acute onset without infectious symptoms makes pneumonia less likely 1

Key Diagnostic Considerations

The British Thoracic Society guidelines emphasize that PE presents in three main clinical patterns, and this patient fits the "pulmonary hemorrhage syndrome" pattern characterized by pleuritic pain and/or hemoptysis 1.

Critical point: The combination of dyspnea, tachypnea, and pleuritic pain is present in 97% of PE cases, and the absence of all three virtually excludes PE 1. This patient has all three features plus hemoptysis, making PE highly probable 1, 2.

Common Pitfalls to Avoid

• Do not dismiss PE based on the presence of hemoptysis alone - while hemoptysis occurs in only 11% of cases, when present with pleuritic pain and dyspnea, it strongly suggests the pulmonary infarction pattern of PE 1, 2
• Do not assume normal oxygen saturation rules out PE - up to 20-40% of PE patients may have normal arterial oxygen pressure 2
• Obesity is a significant risk factor that increases the clinical probability of PE 1

Next Steps

This patient requires immediate objective testing with CT pulmonary angiography (CTPA) as the first-line diagnostic imaging tool 2, along with clinical probability assessment using validated scoring systems (Wells or Geneva criteria) 1.