Bronchial Anthracofibrosis

Bronchial anthracofibrosis is a bronchoscopic and radiological entity defined by black anthracotic pigmentation of the bronchial mucosa with narrowing or obliteration of one or more bronchi. It is found mostly in elderly women who do not smoke, in rural communities exposed to biomass smoke from cooking, and in those with past tuberculosis.

The right middle lobe, upper lobes and lingula are most often involved. The condition is common in parts of Asia, and recognised in sub-Saharan Africa, where indoor wood and charcoal smoke is a major exposure.

Pathophysiology. Inhaled carbon laden particles are carried to peribronchial lymph nodes by macrophages. Pigmented nodes then adhere to and erode through the bronchial wall, causing mucosal pigmentation, fibrosis and stenosis. Concurrent or past tuberculosis causes much of the stenosis, and the pigment itself is a marker of exposure.

Chronic cough, sputum, exertional dyspnoea and wheeze, with haemoptysis in some, in a person with a long history of smoke exposure. Fever, weight loss and night sweats suggest active tuberculosis. Examination may show focal wheeze or reduced air entry over a collapsed lobe.

Massive haemoptysis, stridor and respiratory failure need urgent assessment.

• Flexible bronchoscopy: black pigmented mucosa with narrowed or distorted bronchi, with biopsy showing anthracotic pigment, fibrosis and chronic inflammation.
• CT chest: bronchial narrowing with wall thickening, calcified and enlarged peribronchial lymph nodes, and segmental or lobar collapse, sometimes with bronchiectasis.
• Exclude tuberculosis in every case: sputum or bronchial wash for smear, culture and nucleic acid amplification, and biopsy for granuloma and acid fast bacilli. Tuberculosis is found in a large share of patients in many series.
• Biopsy and brushings to exclude lung cancer, since narrowing and a mass can mimic a tumour.
• Spirometry: obstruction is usual, with reduced FEV1.

Differential diagnosis.

• Simple anthracosis without stenosis (a benign pigment finding in smoke exposed or urban populations)
• Endobronchial tuberculosis
• Lung cancer
• Sarcoidosis
• Silicosis and coal workers pneumoconiosis
• Bronchial stenosis from other causes

• Treat tuberculosis if present: rifampicin 10 mg/kg (maximum 600 mg), isoniazid 5 mg/kg (maximum 300 mg), pyrazinamide 25 mg/kg and ethambutol 15 mg/kg daily for 2 months, then rifampicin and isoniazid daily for 4 months, with pyridoxine 10 to 25 mg daily. Adjust for drug resistance, HIV and organ function.
• Reduce smoke exposure: vented stoves, cleaner fuel and cooking outdoors. Stop smoking where relevant.
• Airflow obstruction: tiotropium 5 micrograms (two inhalations) once daily or a long acting beta agonist, with salbutamol 100 micrograms as needed, and an inhaled corticosteroid only for asthma features or high eosinophils.
• Symptomatic stenosis with collapse or recurrent infection: bronchoscopic balloon dilatation, laser or cryotherapy, or a silicone stent in specialist hands. Systemic corticosteroids have no proven value.
• Vaccination against influenza, pneumococcus and COVID-19, and pulmonary rehabilitation.
• Haemoptysis: tranexamic acid 500 mg to 1 g orally three times daily for up to 5 days (or 1 g intravenously every 8 hours), and bronchial artery embolisation for persistent bleeding.

Monitoring. Repeat bronchoscopy or CT at 2 to 3 months after treatment of tuberculosis or intervention, then yearly while stenosis persists, with spirometry yearly.

Referral and escalation. Refer to a respiratory physician for bronchoscopy and exclusion of cancer, and to interventional pulmonology for stenosis.