In an elderly former cotton‑factory worker with progressive exertional dyspnea, which is the most likely diagnosis: occupational asthma (byssinosis), chronic pneumonia, or aspergillosis?

Occupational Chronic Bronchitis (Byssinosis)

The most likely diagnosis in this elderly former cotton factory worker with progressive exertional dyspnea is occupational chronic bronchitis (byssinosis), not asthma, chronic pneumonia, or aspergillosis. 1

Why Byssinosis is the Most Likely Diagnosis

Cotton Dust Exposure is the Key Risk Factor

• Cotton factory workers are at high risk for byssinosis, which is caused by prolonged inhalation of organic cotton dust and endotoxins 2
• The European Respiratory Society recognizes cotton dust as a specific occupational exposure causing chronic bronchitis and COPD, with approximately 15% of COPD cases attributable to occupational exposures 2, 1
• Byssinosis is formally recognized in the European list of occupational diseases (code 304.02) as "pulmonary diseases caused by inhalation of cotton, linen, hemp, jute, sisal, and bagasse dust and fibers" 1

Progressive Dyspnea After Retirement Fits the Pattern

• The progressive nature of symptoms even after retirement (2 years ago) indicates chronic, irreversible airway damage rather than reversible asthma 1, 3
• Workers with occupational chronic bronchitis develop predominantly fixed airflow obstruction that does not improve during periods away from exposure, unlike occupational asthma which improves on weekends and holidays 2, 3
• The pathology involves persistent airway inflammation and mucus hypersecretion that continues even after exposure cessation 1

Why the Other Diagnoses Are Less Likely

Asthma is Unlikely

• Occupational asthma is characterized by variable and reversible airflow obstruction with improvement of ≥12% and ≥200 mL in FEV1 post-bronchodilator 3
• Asthma symptoms typically improve during weekends and vacations away from work, with acute episodes of dyspnea, chest tightness, and wheezing 3
• This patient has progressive symptoms that persist after retirement, indicating fixed rather than reversible obstruction 1, 3
• The absence of typical asthma features such as episodic wheezing or symptom improvement away from work makes asthma less likely 1

Chronic Pneumonia is Not Supported

• Chronic pneumonia would present with fever, systemic symptoms, and radiographic infiltrates, none of which are mentioned in this case 1
• The occupational history and progressive dyspnea pattern are inconsistent with infectious pneumonia 1

Aspergillosis is Highly Unlikely

• Chronic aspergillosis requires immunocompromise, prior tuberculosis, or pre-existing cavitary lung disease 1
• The clinical presentation does not suggest fungal infection, and there is no mention of these predisposing factors 1
• Cotton dust exposure does not predispose to aspergillosis 1

Diagnostic Confirmation Required

Spirometry is Essential

• The American Thoracic Society recommends that spirometry with bronchodilator testing must be performed to objectively confirm fixed airflow obstruction consistent with COPD (post-bronchodilator FEV1/FVC <0.7) 1, 3
• This distinguishes occupational COPD (minimal reversibility, generally <10% improvement) from occupational asthma (≥12% and ≥200 mL improvement in FEV1) 3

Clinical Criteria for Chronic Bronchitis

• Chronic bronchitis is defined as productive cough for at least 3 months per year for 2 consecutive years 1
• The presence of ronchi on auscultation indicates chronic airway inflammation and mucus hypersecretion, consistent with byssinosis rather than reversible asthma 1

Management Approach

Confirm the Diagnosis

• Obtain detailed occupational history documenting specific cotton dust exposures and duration 1
• Perform spirometry to determine if fixed airflow obstruction is present 1, 3
• Review or obtain chest radiograph to exclude other pathology 1

Treatment Strategy

• Initiate bronchodilator therapy if spirometry confirms airflow obstruction, starting with short-acting beta-2 agonists or anticholinergics as needed 1, 4
• Consider corticosteroid trial if moderate to severe airflow obstruction is documented 1
• Emphasize avoidance of further environmental irritants (though occupational exposure has already ceased) 1, 4

Critical Clinical Pitfall

The diagnosis of occupational chronic bronchitis is commonly missed by clinicians because approximately 15% of chronic bronchitis and COPD cases are attributable to occupational exposures, yet clinicians often fail to take adequate occupational histories 1. Always ask about lifetime occupational exposures in patients presenting with chronic respiratory symptoms.