Immunosuppression-Induced Pulmonary Alveolar Proteinosis Following Bilateral Lung Transplantation

Abstract

<h3>Introduction</h3> Pulmonary alveolar proteinosis (PAP) has been described secondary to immunosuppression-induced macrophage dysfunction following lung transplantation. The incidence of infection is known to be increased in the setting of PAP. We present a case of immunosuppression-associated PAP in a lung transplant recipient with mycobacterium avium complex (MAC) infection, responsive to reduced immunosuppression, serial whole lung lavage, and MAC treatment. <h3>Case Report</h3> A 69-year-old male underwent bilateral lung transplantation for hypersensitivity pneumonitis (HP). He was never treated with mTOR inhibitor therapy. One year post-transplant, he developed intermittent cough and exertional dyspnea. CT scan showed new bilateral peribronchovascular groundglass opacities and interlobular septal thickening, initially concerning for recurrent HP. BAL fluid grew MAC on serial AFB cultures; infection cleared with treatment. Transbronchial biopsy showed A1B0 at the time of MAC infection, which cleared following treatment for acute cellular rejection. He developed increased groundglass opacities with superimposed thickened intra- and interlobular septae in polygonal shapes, "crazy paving" suggestive of pulmonary alveolar proteinosis. Exertional supplemental O2 requirement increased to 10 LPM. Milky-white opaque BAL fluid was noted on bronchoscopy. Transbronchial biopsies showed focal alveolar filling by granular eosinophilic material, consistent with PAP. GM-CSF Ab testing was negative. He had no history of hematologic malignancy, myelodysplastic syndrome, or hematopoietic cell transplantation. Exposure history was negative for dust. <h3>Summary</h3> Whole lung lavage showed cloudy BAL fluid that progressively cleared with continued lavage. Following ACR treatment, immunosuppression was weaned. Groundglass opacities resolved and allograft function improved. He weaned to 4 LPM O2 with exertion with reduction in respiratory symptoms.