Abstract: Objective To improve the understanding of diffuse idiopathic pulmonary neuroendocrine cell hyperplasia (DIPNECH) and primary pulmonary synovial sarcoma (PPSS), and explore the possible correlation between them． Methods Clinical manifestations, pathological change and imaging findings of a patient with DIPNECH and PPSS adm itted to our hospital were retrospectively analyzed with related literature． Results The 20 years old male patient's clinical manifestation were chest congestion, cough and hemoptysis． Contrast enhanced chest CT revealed that patchy shadows appeared in bilateral lungs, cyst with nodule appeared in superior lobe of left lung and a mass in hematoma showed in inferior lobe of left lung． The postoperative pathology examination proved to be diffuse idiopathic pulmonary neuroendocrine cell hyperplasia (DIPNECH) with primary pulmonary monophasic fbrous synovial sarcoma (PPSS)． The patient was followed up for 10 months during which he felt no discom fort and showed no recurrence or metastasis． Conclusion Both DIPNECH and PPSS are extremely rare diseases with complicated and nonspecif c clinical manifestations and imaging fndings． Pathology is essential for conf rmation of the diagnosis．