[Expert recommendations for the diagnosis and treatment of interstitial lung disease caused by novel coronavirus pneumonia].

COVID-19 is an acute infectious disease caused by a newly discovered coronavirus (SARS-CoV2). COVID-19 may manifest bilateral interstitial pneumonia on imaging. About 30%-60% of patients present varying degrees of interstitial changes, while most patients have a good prognosis. Since there's little practical instruct on treating interstitial lung disease (ILD) caused by COVID-19, we present this file as references for all the colleagues fighting with this disease. The primary findings on CT are bilateral, peripheral ground-glass opacities (GGO) and consolidation. Inter-/intra-lobular septal thickening are also common. Subpleural lines and traction bronchiectasis can be seen in some cases which indicate the presence of interstitial fibrosis. Images of severe cases are similar with those in advanced stage of nonspecific interstitial pneumonia (NSIP) and organizing pneumonia (OP). COVID-19 could present the typical two phases of diffuse alveolar damage: acute and proliferative phase on pathology. Massive pulmonary interstitial fibrosis may also be present. HRCT is the best radiological approach for the diagnosis and differential diagnosis of COVID-19, and to assess the presence of ILD. Periodical CT following-up is recommended for patients who present interstitial manifestations. Biomarkers such as KL-6, SP-D, RAGE may also helpful on evaluating the severity of interstitial fibrosis and therapeutic response. We do not suggest applying pulmonary function tests and 6-minute walking test on patients in active stage of the disease. The primary treatments in acute phase are antiviral therapy and supportive treatment. We do not suggest routine use of corticosteroids, while on patients with excessive activation of inflammatory response or rapid progression of lung lesions, a low to medium dosage of corticosteroids could be applied for a short course. Pirfenidone and Nintedanib are encouraged to apply on patients in reparative phase with evidence of progressing fibrosis. Low to medium dosage of corticosteroids is also feasible on patients with NSIP or OP manifestation in this phase, with a relatively longer course. Chinese traditional medicine and rehabilitation medicine may also helpful. Lung transplant surgery is an option for severe pulmonary fibrosis patients. Patients should receive CT following-up after be discharged from hospital, especially those whose pulmonary exudation is not well absorbed. We suggest a routine following-up on month 1, 4 and 10 after discharging, and an extended period for those who have developed irreversible interstitial fibrosis.