Makindo Medical Notes

🫁 Pulmonary Alveolar Proteinosis (PAP) is a rare but potentially treatable lung disorder, presenting with dyspnoea, cyanosis, and finger clubbing. It results from impaired surfactant clearance, leading to alveolar filling with protein-rich material.

📖 About

• Extremely rare interstitial lung disease.
• Potentially reversible with correct treatment (e.g., whole-lung lavage).

⚙️ Aetiology & Pathogenesis

• Failure of alveolar macrophages to clear surfactant → accumulation of proteinaceous material in alveoli.
• Often related to defective or blocked GM-CSF (granulocyte-macrophage colony-stimulating factor) signalling.

⚠️ Risk Factors

• 🚬 More common in smokers.
• 🌫️ Exposure to dusts, fumes, or environmental toxins (esp. in secondary forms).

📂 Classification

• Primary (Idiopathic) – most common; autoimmune (anti–GM-CSF antibodies often present).
• Secondary – due to underlying disease (e.g., leukaemia, lung cancer, chronic infections, toxic exposures).
• Congenital – very rare, due to genetic defects in surfactant protein or GM-CSF receptor.

🩺 Clinical Features

• Progressive exertional breathlessness 🫁.
• Fatigue, weight loss, low-grade fever.
• Fine inspiratory crackles and finger clubbing ✋.
• Cyanosis in advanced disease 🔵.

🔍 Investigations

• 🧪 LDH: typically elevated.
• 📸 CXR: bilateral diffuse alveolar shadowing.
• 🖼️ HRCT: “crazy-paving” pattern (ground-glass + septal thickening).
• 💉 BAL: milky fluid, foamy macrophages, PAS-positive material.
• 🧬 Lung biopsy: alveoli filled with PAS-positive granular material, architecture preserved.
• 🧪 Anti–GM-CSF antibodies: present in primary PAP.

💊 Management

• 👀 Observation if mild/asymptomatic.
• 🚿 Whole-lung lavage – gold standard treatment; significantly improves oxygenation.
• 💉 Exogenous GM-CSF therapy (inhaled or subcutaneous) in autoimmune PAP.
• 🚭 Smoking cessation essential.
• 🦠 Monitor for opportunistic infections (can complicate PAP course).

📚 References

• Pulmonary Alveolar Proteinosis – Khan & Agarwal, Respiratory Care Journal