Makindo Medical Notes

Related Subjects: |Idiopathic Pulmonary Fibrosis |Diffuse Parenchymal Lung disease |Asbestos Related Lung disease |Sarcoidosis |Coal Worker's Pneumoconiosis |Silicosis |Farmer's Lung |Pulmonary Alveolar Proteinosis |Cryptogenic Organising Pneumonia (COP-BOOP) |Extrinsic Allergic alveolitis (Hypersensitivity) |Byssinosis |Pneumoconiosis |Cor Pulmonale |Chest X Ray Interpretation

Pulmonary Alveolar Proteinosis is a rare cause of cyanosis and finger clubbing.

About

• It is a rare lung disorder.
• Potentially treatable with appropriate management.

Aetiology

• Impaired processing of surfactant, leading to accumulation of proteinaceous material in the alveoli rich in surfactant protein and its components.
• Often related to defective granulocyte-macrophage colony-stimulating factor (GM-CSF) signalling.

Risk Factors

• More common in smokers.

Classification

• Primary: Most common form, often idiopathic.
• Secondary: Linked to identifiable causes such as leukaemia, lung cancer, exposure to dust or fumes, or infections.
• Congenital: Extremely rare, related to genetic disorders affecting surfactant metabolism.

Clinical

• Presents with progressive dyspnoea on exertion.
• Associated symptoms include progressive fatigue, weight loss, and low-grade fever.
• Physical examination may reveal fine end-inspiratory crackles and finger clubbing.
• In rare cases, cyanosis and significant finger clubbing can be observed.

Investigations

• Serum lactate dehydrogenase (LDH) level is typically elevated.
• CXR: Shows bilateral alveolar shadowing, often diffuse.
• HRCT scan:characteristic "crazy-paving" pattern with a ground-glass appearance in a geographic distribution.
• Bronchoalveolar lavage (BAL): large foamy macrophages and a milky appearance; positive periodic-acid-Schiff (PAS) staining.
• Lung biopsy: Reveals alveoli partially or completely filled with PAS-positive granular, eosinophilic material with preserved alveolar architecture.
• Antibodies to GM-CSF: Can be detected in primary cases, aiding diagnosis.

Management

• Conservative management for patients with minimal symptoms.
• Whole-lung lavage is the most effective treatment for symptomatic cases, often leading to a significant improvement.
• Correction of GM-CSF deficiency with exogenous GM-CSF therapy is an alternative approach.
• Smoking cessation is crucial, as it can exacerbate the condition.
• Monitor for superinfection, which can complicate the course of the disease.

References

• Pulmonary Alveolar Proteinosis. Ajmal Khan MD DM and Ritesh Agarwal MD DM