Secondary pulmonary alveolar proteinosis during corticosteroid therapy for organising pneumonia associated with myelodysplastic syndrome.

Myelodysplastic syndrome (MDS) is frequently complicated by pulmonary disease. Here, we describe secondary pulmonary alveolar proteinosis (sPAP) that developed during corticosteroid therapy for organising pneumonia (OP) associated with MDS. A 75-year-old woman with MDS complained of cough for 2 weeks. Chest CT showed bilateral patchy consolidations with reversed halo sign. Bronchoalveolar lavage (BAL) examination showed remarkably increased cell density with an increased lymphocyte proportion. Abnormal radiological findings improved rapidly on administration of systemic corticosteroid under the diagnosis of OP; however, they relapsed a few weeks later. Transbronchial lung biopsy showed periodic acid-Schiff stain-positive amorphous materials. Autoantibodies against granulocyte-macrophage colony-stimulating factor (GM-CSF) in serum and BAL fluid (BALF) were both negative, while GM-CSF level in BALF was elevated. The patient was diagnosed with sPAP. When chest radiological findings show exacerbation during corticosteroid therapy for OP in a patient with MDS, physicians should consider sPAP complication as a differential diagnosis.