In a 63-year-old man with a two‑year history of daily productive cough, lifelong nonsmoker, no past medical or family history, former cotton‑factory worker, stable vital signs and rhonchi on lung examination, which diagnosis is most likely: asthma, chronic obstructive pulmonary disease, chronic eosinophilic pneumonia, or chronic pulmonary aspergillosis?

Occupational Chronic Bronchitis (Byssinosis)

The most likely diagnosis is occupational chronic bronchitis (byssinosis), which is a specific form of COPD caused by prolonged cotton dust exposure in textile workers. 1

Clinical Reasoning

This patient's presentation is classic for byssinosis:

• Productive cough for 2 years "most days" meets the clinical definition of chronic bronchitis (productive cough for at least 3 months per year for 2 consecutive years). 1

• The occupational history of working in a cotton factory for many years is the critical diagnostic clue. Cotton dust exposure is a well-established cause of chronic bronchitis, with approximately 15% of chronic bronchitis and COPD cases attributable to occupational exposures. 1, 2

• The timing is highly suggestive: symptoms began precisely when he retired 2 years ago, indicating that chronic airway inflammation persists even after cessation of exposure—a characteristic feature of established occupational chronic bronchitis. 1

• Rhonchi on auscultation indicates chronic airway inflammation and mucus hypersecretion, which are key features of byssinosis rather than the wheezes typically heard in asthma. 1

• Non-smoking status makes this diagnosis more specific, as most COPD is tobacco-related, but cotton workers have significantly increased risk even without smoking (odds ratio 2.51 in workers over 45 years). 2

Why Not the Other Options?

Asthma (Option A) is unlikely:

• Lacks typical asthma features such as episodic symptoms, wheezing, dyspnea, or reversible airway obstruction. 1
• Rhonchi rather than wheezes suggest chronic bronchitis with fixed mucus production rather than reversible airway obstruction. 1
• Constant productive cough for 2 years is not characteristic of asthma, which typically presents with variable symptoms. 1

COPD (Option B) is less precise:

• While technically correct (occupational chronic bronchitis is a subtype of COPD), COPD diagnosis requires spirometry confirmation showing fixed airflow obstruction (post-bronchodilator FEV1/FVC <0.70), which has not been performed. 3, 1
• The specific occupational exposure to cotton dust warrants the more precise diagnosis of byssinosis/occupational chronic bronchitis rather than generic COPD. 1
• Up to 15% of COPD cases are attributable to occupational exposure, but the diagnosis is commonly missed by clinicians who fail to recognize the occupational etiology. 1

Chronic Eosinophilic Pneumonia (Option C) is unlikely:

• Lacks systemic symptoms such as fever, weight loss, or night sweats that typically accompany chronic eosinophilic pneumonia. 1, 4
• No mention of peripheral eosinophilia or infiltrates on chest X-ray, which are characteristic features. 4
• Clinical presentation does not suggest eosinophilic lung disease. 1

Chronic Aspergillosis (Option D) is unlikely:

• Requires immunocompromise, prior tuberculosis, or cavitary lung disease as predisposing factors, none of which are present. 1, 5
• Clinical presentation does not suggest fungal infection. 1
• Aspergillosis typically occurs in patients with chronic lung cavities or severe immunodeficiency. 5

Essential Next Steps

Spirometry with bronchodilator testing must be performed to objectively confirm or exclude fixed airflow obstruction consistent with COPD and to assess severity using FEV1 and FEV1/FVC ratio. 3, 1

If spirometry confirms airflow obstruction:

• Initiate bronchodilator therapy starting with short-acting beta-2 agonists or anticholinergics as needed. 1
• Emphasize avoidance of further occupational exposures or environmental irritants. 1
• Consider corticosteroid trial if moderate to severe airflow obstruction is documented. 1

Additional diagnostic considerations:

• Chest radiograph should be reviewed or obtained if not already done to exclude other pathology. 1
• Detailed occupational history documenting specific exposures should be confirmed. 1

Critical Clinical Pitfall

Occupational chronic bronchitis is commonly missed by clinicians who fail to obtain adequate occupational exposure history. 1 The European Respiratory Society estimates that approximately 15% of chronic bronchitis and COPD cases are attributable to occupational exposures, yet this diagnosis is frequently overlooked. 1 Always inquire about lifetime occupational exposures in patients presenting with chronic respiratory symptoms, particularly in non-smokers.