What are the causes and treatment options for a patient with biapical lung scarring and chronic cough?

Biapical Lung Scarring with Chronic Cough: Causes and Treatment

In a patient with biapical lung scarring and chronic cough, the most critical priority is to rule out reactivation tuberculosis or post-TB complications, followed by systematic evaluation for the common triad of chronic cough causes: upper airway cough syndrome (UACS), asthma, and gastroesophageal reflux disease (GERD).

Causes of Biapical Scarring with Chronic Cough

Primary Concern: Tuberculosis-Related Disease

• Previous or active tuberculosis is the most important consideration given the biapical distribution of scarring, which is the classic pattern for TB 1
• Post-TB complications including bronchiectasis, endobronchial abnormalities, or retained sutures can cause chronic cough as a major manifestation 2
• Even with treated TB from decades prior, complications can emerge later 1

Other Causes of Apical Scarring

• Sarcoidosis can present with apical scarring and chronic cough 2
• Interstitial lung diseases including idiopathic pulmonary fibrosis (though typically lower lobe predominant) can cause progressive scarring and chronic cough 3
• Fungal infections (histoplasmosis, aspergillosis) may cause apical scarring 4
• Pneumoconiosis from occupational exposures 4

Common Causes of Chronic Cough (Often Coexist)

Even with radiographic abnormalities, the three most common causes of chronic cough—UACS, asthma, and GERD—account for 90% of chronic cough diagnoses and frequently occur in combination 2, 5

• These conditions can be "clinically silent" apart from cough itself 2
• Multiple simultaneous causes occur in 59% of chronic cough cases 5

Diagnostic Approach

Immediate Evaluation

• Obtain sputum for acid-fast bacilli (AFB) smear and culture to exclude active TB, especially given biapical scarring 4
• Review medication list: If taking an ACE inhibitor, discontinue immediately as this causes chronic cough with median resolution time of 26 days 2, 6
• Assess smoking status: If current smoker, smoking cessation resolves cough in majority within 4 weeks 2, 6

High-Resolution CT Scan

• HRCT is essential to characterize the apical scarring pattern and identify complications like bronchiectasis, cavitation, or endobronchial lesions 2
• Helps distinguish post-TB changes from active disease or alternative diagnoses 4

Bronchoscopy Considerations

• Consider bronchoscopy if:
  • Hemoptysis is present 2
  • Concern for endobronchial tumor or retained foreign material 2
  • Need for direct visualization of airways and sampling 2

Treatment Algorithm

Step 1: Address TB Risk and Smoking

• If active TB suspected or confirmed: Initiate multi-drug anti-tuberculous therapy per standard protocols 7
• If smoking: Strongly advise cessation 2, 6
• If on ACE inhibitor: Switch to alternative antihypertensive 2, 6

Step 2: Empiric Treatment for Common Causes

Even with abnormal chest radiograph, systematically treat the common triad 2

First-Line: Treat UACS

• Initiate first-generation antihistamine plus decongestant (e.g., chlorpheniramine/pseudoephedrine) 2, 6, 8
• Expect improvement within 1-2 weeks, though complete resolution may take longer 6

Second-Line: Add Asthma Treatment

• Start inhaled corticosteroids (ICS) combined with long-acting β-agonists (LABA) such as fluticasone/salmeterol twice daily 6
• Consider this early if wheezing, dyspnea, or bronchial hyperresponsiveness suspected 2
• Monitor response within 2-4 weeks 6

Third-Line: Add GERD Treatment

• Initiate proton pump inhibitor (PPI) therapy if incomplete response to above treatments 6, 8
• Continue all partially effective treatments as cough is often multifactorial 6

Step 3: Consider Non-Asthmatic Eosinophilic Bronchitis (NAEB)

• NAEB should be considered early as it responds predictably to inhaled corticosteroids 2
• Diagnosed by induced sputum analysis for eosinophils 2
• Prevalence ranges from 13-33% in some series 2

Step 4: Specialized Evaluation if Refractory

• Pulmonology referral if cough persists despite sequential empiric therapy 6
• Consider uncommon causes including:
  • Tracheobronchomalacia or airway stenosis 2
  • Broncholithiasis (calcified lymph nodes eroding into airways) 2
  • Retained foreign material or sutures from prior surgery 2

Critical Pitfalls to Avoid

• Do not rely on cough characteristics (timing, character, sputum production) to guide diagnosis—these lack diagnostic sensitivity and specificity 2, 5
• Do not assume normal spirometry excludes asthma—consider bronchoprovocation challenge if baseline testing is normal 6
• Do not stop partially effective treatments when adding new therapies, as multiple simultaneous causes are common 6, 5
• Do not delay TB evaluation in patients with apical scarring, especially with risk factors or endemic exposure 2, 4
• Do not overlook lung cancer in smokers with new or changed cough pattern, even with known scarring—cancer causes 2% of chronic cough cases 2

Special Considerations for Biapical Scarring

The presence of biapical scarring changes the clinical context compared to patients with normal chest radiographs 2

• Post-TB bronchiectasis can cause chronic suppurative cough requiring different management 2
• Fibrotic lesions consistent with healed TB warrant consideration of isoniazid preventive therapy if risk factors for reactivation exist 7
• Scarring may predispose to recurrent infections requiring antimicrobial therapy 2