Secondary Pulmonary Alveolar Proteinosis Following Acute Myeloid Leukemia that Progressed from Myelodysplastic Syndrome-A Case Report

Pulmonary alveolar proteinosis (PAP) is a pulmonary disease characterized by alveolar accumulation of surfactants composed of proteins and lipids due to defective surfactant clearance by alveolar macrophages. Secondary PAP comprises approximately 10% of cases, and the most common underlying conditions are hematological disorders. These patients often have a poor prognosis. Treatment of secondary PAP is mainly focused on the underlying diseases. We encountered a patient with acute myeloid leukemia that developed from myelodysplastic syndrome - refractory anemia with excess blasts in transformation (MDSRAEBT) who was diagnosed as having secondary PAP based on bronchoalveolar lavage fluid findings. The patient was considered initially as having atypical infection, and died of multiple organ failure in the end due to fungemia. We need to be more aware of the possibility of secondary PAP in cases of MDS presenting with lung complications, especially in patients in the leukemic phase, as secondary PAP indicates a poor outcome.