What could be causing pain in my left upper thorax near the lung?

Left Upper Thoracic Pain: Diagnostic Approach

You need immediate evaluation to rule out life-threatening causes, particularly cardiac ischemia, pulmonary embolism, and aortic dissection, before considering less urgent pulmonary and chest wall etiologies. 1

Immediate Life-Threatening Causes to Exclude First

Cardiac Ischemia

• Obtain an ECG within 10 minutes if you have any cardiac risk factors (age >55 for men, >65 for women, diabetes, hypertension, smoking, family history) 1
• Cardiac chest pain typically presents as substernal pressure, squeezing, or heaviness that may radiate to the neck, jaw, or left arm—but can present atypically, especially in women, elderly, and diabetics 2, 1
• Measure cardiac troponin immediately if there is any concern for acute coronary syndrome 1
• Go to an emergency department immediately if you experience associated sweating, nausea, shortness of breath, or lightheadedness 1

Pulmonary Embolism

• Consider this if you have acute dyspnea, tachycardia, or pleuritic chest pain (pain that worsens with breathing) 1
• Risk factors include recent immobilization, surgery, cancer, or leg swelling 1

Aortic Dissection

• Characterized by sudden-onset "ripping" or "tearing" pain radiating to the back 1
• Check for pulse differences between your arms—this is a critical warning sign 1

Pneumothorax

• Presents with sudden sharp pain, shortness of breath, and pain worsening with inspiration 1
• More common in tall, thin individuals and smokers 3

Pulmonary Causes of Left Upper Thoracic Pain

Pleuritic Pain (Pain Related to Breathing)

If your pain worsens with deep breathing or coughing, this suggests pleural irritation or inflammation 3, 4

• Pleurisy/Pleuritis: Sharp, stabbing pain that worsens with inspiration, often following respiratory infection 3
• Pneumonia: Pain associated with fever, cough, and sputum production 3
• The visceral pleura (lung surface) has no pain receptors, so lung pain always comes from parietal pleura irritation, chest wall involvement, or mediastinal structures 4

Lung Cancer Considerations

• Nonspecific chest discomfort is common in lung cancer, while pleuritic pain suggests pleural invasion 2
• Localized chest wall pain may indicate tumor extension into the chest wall or ribs 2
• Left-sided tumors can cause referred pain through vagus nerve compression, though this is rare 5
• If you are a smoker with persistent chest discomfort, even without other symptoms, lung cancer must be excluded 2
• Superior sulcus (Pancoast) tumors in the left upper lung can cause shoulder and arm pain from brachial plexus invasion 2

Pulmonary Hypertension and Chronic Lung Disease

• These conditions cause more constant, non-pleuritic chest pain unrelated to breathing 3
• Pain in COPD exacerbations should always prompt evaluation for cardiac causes 3

Chest Wall and Musculoskeletal Causes

Costochondritis/Chest Wall Pain

• Tenderness to palpation that reproduces your exact pain is the hallmark finding 6
• Pain is typically sharp or stabbing, localized to a specific area 6
• First-line treatment is NSAIDs for 1-2 weeks 6

Herpes Zoster (Shingles)

• If you have burning, tingling, or skin sensitivity in addition to chest pain, herpes zoster is the leading diagnosis 1
• Pain follows a dermatomal distribution (band-like pattern), is strictly unilateral, and does not cross the midline 1
• A vesicular rash may appear days after pain onset 1

Critical Red Flags Requiring Emergency Evaluation

Seek immediate emergency care if you experience: 1

• Associated sweating, nausea, vomiting, or shortness of breath
• Lightheadedness, syncope, or confusion
• Pain that is severe, sudden-onset, or "ripping/tearing" in quality
• Hemoptysis (coughing up blood)
• Fever with productive cough

Recommended Diagnostic Pathway

1. If you have cardiac risk factors or concerning features, go to the emergency department for ECG and troponin 1
2. If pain is clearly pleuritic (worse with breathing), you need chest imaging (chest X-ray or CT) to evaluate for pneumonia, pneumothorax, or pleural disease 3, 4
3. If pain is reproducible with palpation of the chest wall, musculoskeletal causes are likely, but cardiac causes must still be excluded first 6
4. If you are a smoker or have risk factors for lung cancer, persistent chest discomfort warrants chest CT even without other symptoms 2

Common Pitfall to Avoid

Many patients dismiss chest pain as "not cardiac" because it doesn't match their expected symptoms (central crushing chest pain), leading to dangerous delays 7, 8. Cardiac pain can present as sharp, stabbing, or localized left chest pain, especially in women and diabetics 1. When in doubt, seek immediate evaluation—the consequences of missing acute coronary syndrome, pulmonary embolism, or aortic dissection are catastrophic 1.