C KHOR1, K KUMAR1
1Gosford Hospital, Gosford, Australia
Background:Pulmonary alveolar proteinosis (PAP) is a diffuse lung disease characterised by accumulation of surfactant. Clearance of surfactant by alveolar macrophages is regulated by granulocyte macrophage colony stimulating factor (GM-CSF). Autoimmune PAP due to GM-CSF antibodies is the most common cause of PAP in adults. Secondary causes include dust exposure, haematological malignancy and immunosuppressive medications.
Case report:A 52 year old man developed progressive shortness of breath, hypoxia and productive cough one year post living unrelated renal transplant for polycystic kidney disease. This is in the context of BK virus nephropathy at three months post-transplant requiring a change in immunosuppressants from tacrolimus and mycophenolate to cyclosporine and leflunomide. A high resolution computed tomography (HRCT) of the chest demonstrated bilateral peri-hilar ground glass opacities. Pneumocystis jiroveci pneumonia (PJP) treatment was commenced with no benefit. Bronchoscopy with bronchoalveolar lavage was inconclusive. The patient underwent a transbronchial biopsy which was positive for periodic acid-Schiff (PAS) proteinaceous material confirming the diagnosis of pulmonary alveolar proteinosis.There was no evidence of haematological malignancy clinically and on bone marrow biopsy. Immunosuppression was changed to tacrolimus and mycophenolate with no improvement in respiratory symptoms. Serum GM-CSF antibodies subsequently returned positive with titres rising from 0.50 to 0.66 suggestive of autoimmune PAP. Rituximab, intravenous immunoglobulin and plasma exchange were considered however patient responded clinically and radiologically with total lung lavage.
Conclusions:Pulmonary alveolar proteinosis is an uncommon but important differential diagnosis in patients with a subacute presentation of respiratory symptoms and ground glass changes on HRCT especially in the context of PJP therapy failure.
Candice Khor is a first year renal advance trainee with the East Coast Renal Network currently based at Gosford Hospital in New South Wales, Australia.