What is the diagnosis and treatment for a patient with exertional dyspnea, dry cough, and bilateral burning pain for 2 years, with normal serum creatinine and no diabetes?

Diagnosis and Management of Chronic Exertional Dyspnea with Dry Cough and Bilateral Burning Pain

The most likely diagnosis is interstitial lung disease (ILD), specifically hypersensitivity pneumonitis or idiopathic pulmonary fibrosis, and you should immediately obtain high-resolution CT chest imaging and pulmonary function testing with DLCO to establish the diagnosis and assess disease severity. 1

Initial Diagnostic Approach

Essential History Elements

• Duration and progression of symptoms: The 2-year timeline with exertional dyspnea and dry cough strongly suggests chronic interstitial lung disease rather than acute processes 1
• Exposure history is critical: Systematically inquire about occupational exposures (birds, mold, organic dusts), environmental exposures at home (humidifiers, water damage, feather bedding), and hobbies that may cause hypersensitivity pneumonitis 1
• Bilateral burning pain: This atypical symptom may represent chest wall pain from chronic coughing, pleuritic pain from peripheral lung involvement, or neuropathic pain—document exact location and relationship to breathing 1
• Exclude cardiac causes: Ask specifically about orthopnea, paroxysmal nocturnal dyspnea, peripheral edema, and number of pillows needed for sleep 2

Physical Examination Priorities

• Auscultate for fine bibasilar crackles ("Velcro rales"): This finding is highly suggestive of pulmonary fibrosis and present in most ILD patients 1, 3
• Assess for digital clubbing: Present in 25-50% of idiopathic pulmonary fibrosis cases 1
• Cardiac examination: Evaluate for elevated jugular venous pressure, S3 gallop, and peripheral edema to exclude heart failure as primary cause 2

Mandatory Initial Testing

First-Line Diagnostic Studies

• High-resolution CT chest (HRCT) without contrast: This is the single most important test—look for ground-glass opacities, reticulation, honeycombing, or traction bronchiectasis that define fibrotic vs. non-fibrotic ILD 1, 4
• Pulmonary function testing with spirometry and DLCO: Expect restrictive pattern (reduced FVC) with reduced DLCO in ILD; normal spirometry does NOT exclude ILD 1
• Brain natriuretic peptide (BNP): Order to exclude heart failure, as BNP <100 pg/mL has 96-99% sensitivity for ruling out cardiac causes 2
• Complete blood count and basic metabolic panel: Confirm normal creatinine as stated, but also assess for anemia or eosinophilia that may suggest specific ILD subtypes 5
• Chest radiograph: May show interstitial infiltrates but HRCT is far superior for ILD diagnosis 1, 2

Second-Line Testing Based on Initial Results

• Serum KL-6/MUC1 marker: Elevated in 70-100% of patients with active interstitial pneumonitis and useful for monitoring disease activity 3
• Autoimmune serology panel: If connective tissue disease-associated ILD suspected (ANA, RF, anti-CCP, myositis panel) 1
• Hypersensitivity pneumonitis panel: Serum precipitins for common antigens if exposure history suggests HP 1

Diagnostic Algorithm Based on HRCT Findings

If HRCT Shows Fibrotic Pattern (Reticulation, Traction Bronchiectasis, or Honeycombing)

• Prognosis is significantly worse: Fibrotic HP patients have 4.35 times increased risk of death compared to non-fibrotic HP 1
• Extent of fibrosis predicts mortality: Patients with >40% lung involvement have 83% mortality vs. 21% with <10% involvement 1
• Refer to pulmonology immediately for consideration of antifibrotic therapy (nintedanib or pirfenidone) and possible lung biopsy 1, 5

If HRCT Shows Non-Fibrotic Pattern (Ground-Glass Opacities Without Fibrosis)

• Better prognosis: Non-fibrotic HP has significantly better survival (HR 0.22) compared to fibrotic disease 1
• Identify and eliminate inciting antigen: This is the most important intervention—89% of non-fibrotic HP cases have identifiable exposure 1
• Consider empiric corticosteroid trial: Prednisone 0.5-1 mg/kg/day with taper if HP suspected, but only AFTER securing tissue diagnosis or high clinical certainty 4

Treatment Approach

Address Underlying Cause First

• Antigen avoidance is paramount for hypersensitivity pneumonitis: Complete removal from exposure can lead to disease resolution in non-fibrotic cases 1
• Optimize any disease-modifying therapy: For fibrotic ILD, antifibrotic agents reduce disease progression 5

Symptomatic Management of Dyspnea

• Pulmonary rehabilitation and exercise training: Strongly recommended for all patients with chronic dyspnea and reduced functional capacity 1, 5
• Supplemental oxygen if hypoxemic: Measure oxygen saturation at rest and with exertion; provide supplementation to maintain SpO2 >90% 5
• Opioids for refractory dyspnea: Morphine 2.5-10 mg PO every 2 hours as needed is first-line pharmacologic treatment for breathlessness not relieved by treating underlying disease 5

Management of Dry Cough

• Treat underlying ILD: Cough often improves with disease-specific therapy 1
• Exclude upper airway cough syndrome (UACS), asthma, and GERD: These are the three most common causes of chronic cough and may coexist with ILD 1
• Trial of empiric GERD therapy: Consider PPI therapy if any reflux symptoms, as GERD can present with cough alone ("silent GERD") 1, 6

Critical Pitfalls to Avoid

Common Diagnostic Errors

• Do not rely on normal chest X-ray to exclude ILD: HRCT is mandatory for proper evaluation 1
• Do not assume normal spirometry excludes ILD: Early ILD may have normal FEV1/FVC with isolated DLCO reduction 1
• Do not delay HRCT while pursuing empiric treatments: The 2-year symptom duration demands definitive imaging now 1, 4

Treatment Considerations

• Avoid prolonged empiric corticosteroids without diagnosis: The case example showed initial response but later worsening, suggesting either wrong diagnosis or progressive fibrotic disease 4
• Symptom duration does NOT predict prognosis: Studies show no association between symptom chronicity and survival in HP 1
• Bilateral burning pain requires specific attention: While focusing on respiratory diagnosis, ensure adequate pain assessment and management as this may significantly impact quality of life 1

When to Refer

• Immediate pulmonology referral if: HRCT shows fibrotic changes, progressive symptoms despite initial therapy, or diagnostic uncertainty after initial workup 1, 5
• Consider palliative care consultation: For patients with advanced fibrotic disease and refractory symptoms to optimize quality of life 5