What is the differential diagnosis for an adult or older adult patient with pleuritic pain, cough, and shortness of breath (SOB) without typical cough and cold symptoms, and no cardiac problems, considering their medical history, including any history of smoking, exposure to pollutants, or previous lung conditions?

Differential Diagnosis for Pleuritic Pain with Cough and Shortness of Breath

The most critical diagnoses to exclude immediately are pulmonary embolism, pneumonia, and pneumothorax, as these represent life-threatening conditions that can present with pleuritic pain, cough, and dyspnea without typical upper respiratory symptoms. 1, 2, 3

Life-Threatening Conditions (Rule Out First)

Pulmonary Embolism

• PE must be the primary consideration when pleuritic chest pain occurs with dyspnea and cough, particularly without preceding viral prodrome 1, 3
• Pleuritic pain occurs in 52% of PE cases, caused by pleural irritation from distal emboli leading to pulmonary infarction 2, 3
• Dyspnea is present in approximately 80-85% of PE patients and is often the most prominent symptom 1, 3
• Cough occurs in 20% of PE cases 1
• Critical risk factors to assess: immobilization in past 4 weeks, history of DVT/PE, malignancy, recent surgery, prolonged travel 1, 3
• The combination of tachypnea, pleuritic pain, and arterial hypoxemia strongly suggests PE; absence of all three virtually excludes it 3
• Fever can be present in approximately 7% of PE cases, which can mislead toward infectious diagnosis 3

Pneumonia

• Community-acquired pneumonia presents with cough, dyspnea, and pleuritic chest pain without necessarily having upper respiratory prodrome 1
• Pleuritic pain with localized findings suggests pneumonia with pleural involvement 2
• Key distinguishing features: fever, productive cough, crackles on auscultation, and consolidation on chest radiograph 1
• Elderly patients may lack typical symptoms despite having pneumonia on imaging 1

Pneumothorax

• Presents with acute onset dyspnea and sharp pleuritic pain 2
• Examination finding: unilateral absence or decreased breath sounds 2
• More common in tall, thin individuals and smokers 2

Other Pulmonary Causes

Pleuritis/Pleural Disease

• Sharp, stabbing pain that worsens with deep breathing, coughing, or respiratory movements 2
• May present with pleural friction rub on examination (sounds like creaking leather, biphasic, not cleared by coughing) 2
• Can occur from viral infections, autoimmune conditions, or post-infectious inflammation 2

Pulmonary Tuberculosis

• Consider in patients with risk factors: immunosuppression, endemic area exposure, homelessness, incarceration 4
• Typically presents with chronic cough (>3 weeks), night sweats, weight loss, but can present acutely 4

Lung Bullae with Infection

• Particularly in heavy smokers or cannabis users 5
• Chest imaging may show fluid levels within bullae 5
• Associated with moderate airflow obstruction on pulmonary function testing 5

Cardiac Causes (Despite "No Cardiac Problems")

Pericarditis

• Sharp, pleuritic chest pain that improves sitting forward and worsens lying supine 2
• May follow viral illness or occur in autoimmune conditions 2
• Can present with friction rub and widespread ST elevation with PR depression on ECG 2
• Important: Can occur as complication of pneumonia (up to 10% of bacteremic pneumococcal pneumonia) 2

Chronic Lung Disease Exacerbation

Asthma or COPD Exacerbation

• Up to 45% of patients presenting with acute cough may have underlying asthma or COPD 1
• Predictive features: wheezing, prolonged expiration, significant smoking history, history of allergy 1
• May present without typical "cold" symptoms 1

Diagnostic Algorithm

Immediate Assessment

1. Assess for PE risk factors (immobilization, malignancy, prior VTE, surgery) 1, 3
2. Vital signs: tachypnea, tachycardia, hypoxemia strongly suggest PE or severe pneumonia 3
3. Physical examination:
   • Unilateral decreased breath sounds → pneumothorax 2
   • Crackles → pneumonia 1, 2
   • Pleural friction rub → pleuritis, pneumonia with pleural involvement 2
   • Reproducible chest wall tenderness → consider musculoskeletal, but does NOT exclude serious pathology (7% with reproducible pain have ACS) 2

Initial Diagnostic Testing

1. Chest radiograph (PA and lateral): essential first-line imaging to evaluate for pneumonia, pneumothorax, pleural effusion, or masses 1
2. D-dimer: if PE suspected and low-to-intermediate clinical probability 3
3. CT pulmonary angiography: if high clinical suspicion for PE or D-dimer positive 1, 3
4. ECG: to evaluate for pericarditis (widespread ST elevation with PR depression) or PE (S1Q3T3 pattern, though insensitive) 2, 3
5. Complete blood count, inflammatory markers: to assess for infection 1
6. Oxygen saturation/arterial blood gas: if respiratory distress present 3

Critical Pitfalls to Avoid

• Do not dismiss PE because patient has cough or low-grade fever - PE can present with these symptoms 3, 6
• Do not assume viral pleuritis without imaging - PE frequently mimics infectious pleuritis 6
• Do not wait for diagnostic confirmation if PE highly suspected - initiate anticoagulation immediately based on clinical suspicion 3
• Do not attribute all symptoms to single diagnosis prematurely - more than 30% of chronic dyspnea cases are multifactorial 7
• Elderly patients may have pneumonia despite normal physical examination - maintain low threshold for chest radiograph 1

Special Considerations by Patient Population

• Smokers: consider lung bullae with infection, COPD exacerbation, pneumothorax, lung cancer 1, 5
• Occupational exposures: consider occupational asthma, hypersensitivity pneumonitis, asbestos-related pleural disease 1
• Aspiration risk (stroke, dementia, dysphagia): consider aspiration pneumonia 1