Pulmonary Alveolar Proteinosis After Lung Transplantation

Abstract

<h3>Introduction</h3> Secondary pulmonary alveolar proteinosis (PAP) is a minor subtype of the disease entity with poorer prognosis than common autoimmune PAP. It has been reported to complicate hematologic disorders, immunodeficiency, and infections. However, PAP associated with lung transplantation is not well recognized. Here, we report two cases of PAP after lung transplantation. <h3>Case Report</h3> Case 1: A four-year-old boy underwent a double-lung transplantation. He was maintained standard immunosuppressive regimen. The immediate post-operative course was uneventful. On post-operative day (POD) 23, chest computer tomography (CT) scan showed ground-glass opacities (GGOs) with interlobular septal thickening, along with worsening oxygenation. An acute rejection was clinically suspected, and the patient underwent steroid pulse therapy. It improved temporarily, but worsened again within a week. Despite the repeated steroid pulse, administration of anti-thymocyte globulin and inhibitors of the mammalian target of rapamycin, the situation gradually deteriorated and eventually complicated by infectious diseases. The patient died from respiratory failure on POD 248. At autopsy, diffuse intra-alveolar eosinophilic materials stained by surfactant apoprotein A immunohistochemistry were found and led to a diagnosis of PAP. Case 2: A 52-year-old man underwent double-lung transplantation. He was maintained standard immunosuppressive regimen. The post-operative course was uneventful. On POD 99, routine chest CT scan showed bilateral centrilobular ground-glass opacities mimicking rejection. A diagnostic trial of steroid increase was ineffective. Bronchoalveolar lavage fluid analysis and transbronchial biopsy demonstrated intra-alveolar eosinophilic materials which stained by periodic acid-Schiff. He was diagnosed with PAP and followed up with tapering immunosuppression in the standard manner, resulting in a clinical and radiological improvement. <h3>Summary</h3> PAP is a rare cause of graft dysfunction after lung transplantation. In case 1, the patient was misdiagnosed as acute rejection, and immunosuppression was intensified, which led to fatal consequences. PAP after lung transplantation is potentially a transient or slowly progressive pathology as seen in case 2. Transplant physicians should be aware of this rare complication.