What is desquamative interstitial pneumonia? Desquamative interstitial pneumonia (DIP) is a chronic interstitial lung disease that is classified as a smoking-associated interstitial lung disease. Its pathogenesis is closely related to smoking, and the histopathology of the lung shows a diffuse and uniform distribution of pulmonary macrophages in the alveolar lumen. The macrophages that accumulate in the alveolar cavity were once mistaken for shed alveolar epithelial cells, hence the name “desquamative” interstitial pneumonia. What are the clinical manifestations of desquamative interstitial pneumonia? Most patients seek medical attention for active dyspnea and cough, with some patients experiencing chest pain and weight loss. Pleural lesions and spontaneous pneumothorax are less common. Severe cases may present with respiratory failure. Inspiratory phase bursting sounds can be heard in the base of both lungs on lung examination, and pestle-like fingers (toes) are seen in half of the patients. How is desquamative interstitial pneumonia diagnosed? Patients who smoke or have occupational or environmental exposures present with active dyspnea or dry cough, pulmonary function suggesting restrictive ventilation dysfunction and/or diffusion disorders, diffuse ground glass and grid shadows on high resolution CT of the chest, and in severe cases, cellular lung with or without distended bronchial dilatation, may suggest desquamative interstitial pneumonia. Surgical thoracoscopy or open lung biopsy is performed to obtain lung tissue to confirm the diagnosis. How is desquamative interstitial pneumonia treated? Smoking cessation helps. Most patients need glucocorticoid therapy, especially if they are symptomatic and have pulmonary dysfunction. What is the prognosis for desquamative interstitial pneumonia? The annual and 10-year survival rates are 95% and 70%, respectively. Patients will progress slowly, with a few patients having a poor prognosis. Patients with worsening disease and a poor prognosis tend to occur in those who continue to smoke or are passive smokers. Therefore, patients with desquamative interstitial pneumonia should avoid tobacco exposure including smoking or passive smoking.