Two cases will be presented.Imaging findings,diagnosis and differential diagnosis,and key points of each case will be illustrated at detail.Differential diagnosis of sinonasal mass is very difficult since a variety of diseases including malignant tumors,benign tumors,some inflammatory diseases and polyps share similar imaging findings.Squamous cell carcinoma,lymphoma,adenoid cystic carcinoma,esthesioneuroblastoma,and adenocarcinoma are common malignant tumors.