INTERSTITIAL LUNG DISEASE ASSOCIATED WITH ASIAN DUST STORM EXPOSURE

Abstract

INTRODUCTION: Asian dust or yellow sand storms are seasonal meteorological phenomenon originating in the deserts of Mongolia and Northern China that affect much of East Asia. Exposure to ambient air particulate matter (PM) from dust storms has been associated with significant pulmonary morbidity and mortality. Desquamative Interstitial Pneumonia (DIP) is an idiopathic interstitial pneumonia that typically affects cigarette smokers. We present a unique case of a nonsmoker who developed DIP necessitating lung transplantation after exposure to an Asian dust storm event in South Korea. CASE PRESENTATION: A 47 year old male lifetime nonsmoker was emergently referred for lung transplant evaluation for progressive hypoxemia due to pulmonary fibrosis. Patient was in his usual state of health until he was exposed to yellow dust storm while working in South Korea one year before presentation. He developed acute shortness of breath and cough immediately after the dust storm which never completely resolved. Subsequent workup including CT chest showed diffuse ground glass infiltrates. Bronchoscopy was macroscopically normal with a lymphocyte predominant lavage with no transbronchial biopsies preformed. He was empirically treated with systemic steroids with no improvement in his symptoms. Patient continued to worsen both subjectively and objectively and underwent a surgical lung biopsy which showed DIP type pattern. Following the surgical lung biopsy, patient began to have worsening hypoxemia leading to prolonged hospitalization and transfer to our institution for emergent lung transplant evaluation. His clinical condition worsened after developing an iatrogenic pneumothorax and he emergently underwent bilateral lung transplantation on ECMO support as a bridge to transplant due to his rapid deterioration. The explanted lung pathology demonstrated an abundance of alveolar macrophages within the alveolar spaces and many of the macrophages appeared to contain some pigment. Polirization of multiple tissue blocks showed minimal birefringent material. The pathology was felt to be consistent with an exposure related injury with DIP pattern. DISCUSSIONS: DIP, typically seen in male smokers who present in their 3rd or 4th decade of life, is considered to be a non-specific pulmonary reaction to injury, and is pathologically characterized by the presence of numerous macrophages within the airspace with minimal fibrosis. DIP is known to occur in non-smokers most commonly in the context of pneumoconiosis, drug reactions or inborn errors of metabolism. Asian or yellow dust storm, a weather phenomenon originating in the desert regions of China and Mongolia, when combined with air pollutants from human activities have resulted in increased pulmonary morbidity and mortality mainly in patients with underlying lung disease (COPD or asthma). In animal studies, exposure to concentrated PM from an actual Asian dust storm has been shown to cause lung inflammation and injury associated with elevated IL-6 in the bronchoalveolar lavage fluid. There is a paucity of knowledge in the English literature regarding the association of interstitial lung disease with exposure to Asian dust storm but scant evidence does exist in the Chinese literature. Our patient had no known lung disease and had an active life style prior to his exposure to the PM from the Asian dust storm in 2007. He developed acute respiratory symptoms after the exposure with CT imaging indicating indicative of an inflammatory reaction which progressed on a relentless course necessitating bilateral lung transplantation. This is the only reported case of bilateral lung transplant for Asian dust exposure in the literature with the histopathology of the explanted lungs being consistent with a DIP type reaction to an exposure related injury. CONCLUSION: In susceptible patients, exposure to particulate matter from Asian dust storm may be associated with DIP type pattern of lung injury.