Role of granulocyte‐macrophage colony‐stimulating factor in pulmonary fibrosis following pulmonary alveolar proteinosis

Pulmonary alveolar proteinosis (PAP) is a rare diffuse lung disease characterized by accumulation of lipoproteinacious material in alveoli, with distinct features on high resolution computed tomography and biopsy. Its association with pulmonary fibrosis is infrequently encountered, and a clear understanding of the underlying pathogenesis is yet to be established. We report the case of a 48‐year‐old woman with known autoimmune PAP (aPAP) first diagnosed 20 years ago, who presented with worsening hypoxemia and radiological features consistent with pulmonary fibrosis, after many years of stable disease. We present a review of previously considered mechanisms of causation behind such changes, and in particular, postulate the role of granulocyte‐macrophage colony‐stimulating factor deficiency in pulmonary fibrosis seen in aPAP.