Abstract: Objective To investigate the clinical symptoms, imaging manifestations, pathological features, treatment and prognosis of acute fibrinous and organizing pneumonia(AFOP)to enhance the diagnosis and treatment of this disease. Methods The clinical data of 3 AFOP patients were collected, and the relevant literature reports were reviewed. Results All of the 3 cases were idiopathic and subacute. Pathological histology showed intra-alveolar fibrin deposition forming eosinophilic fibrin “balls”. All patients had a good clinical response to glucocorticoid therapy. Clinical data of 86 reported AFOP cases including 46 males and 40 females(aged 53.8±15.9 years)were also analyzed. No risk or predisposing factors were observed in 35 cases, while the other 51 cases were secondary AFOP. Autoimmune and hematological diseases were the most common comorbidity. Most common symptoms were dyspnea, cough and fever. Consolidation was the most common imaging pattern, followed by ground-glass opacity and nodules. Most cases were confirmed by minimally invasive procedures including percutaneous lung puncture biopsy or transbronchial lung biopsy. Corticosteroids were the main drug treatment, but the final options depended on the etiology and severity of disease. Conclusion AFOP is a rare noninfectious pulmonary disease with a lack of specificity in clinical presentation and imaging. Pathology has unique histological features, and should be differentiated from other lung injury diseases.

Key words: Acute fibrinous and organizing pneumonia, Histology, Glucocorticoid