Objective       To study and summarize the cause

clinical feature

chest imaging feature

key points of differential diagnosis and laboratory examination of diffuse pulmonary infiltrates (DPI)

so as to improve clinicians’ understanding and levels of diagnosis and treatment of DPI.       Methods        Clinical data of 82 patients who were diagnosed as DPI in our hospital from Mar 2010 to Jul 2011 were prospectively analyzed

including medical history

signs

chest imaging

laboratory examination and lung biopsy pathological examination.       Results       The causes of 82 DPI patients included infectious disease (30/82

36.6%)

idiopathic interstitial pneumonia (IIP) (17/82

20.7%)

connective tissue disease (CTD) pulmonary infiltrates (9/82

11%)

lung cancer (6/82

7.3%)

vasculitis (4/82

4.9%)

pulmonary edema (4/82

4.9%)

sarcoidosis (3/82

3.7%)

pulmonary alveolar proteinosis (2/82

2.4%)

lymphoma (1/82

1.2%)

alveolar microlithiasis (1/82

1.2%)

radiation pneumonitis (1/82

1.2%)

aspiration pneumonia (1/82

1.2%)

drug-induced pulmonary fibrosis (1/82

1.2%)

diffuse panbronchiolitis (1/82

1.2%) and idiopathic pulmonary hemosiderosis syndrome (1/82

1.2%). Patients with different causes of DPI had their own characteristics in clinical history

signs

chest imaging

laboratory tests and lung biopsy pathology etc.       Conclusion       Causes of DPI were complicated

and infectious diseases

IIP and CTD were the common causes. Fever and velcro rales were important clinical features

and ground glass

grid shadow and nodules were imaging characteristics for differential diagnosis. Infectious diseases should focus on etiology examination

while non-infectious diseases should focus on special laboratory and pathological examinations.