Abstract: Objective To explore the clinical, pathological, imaging characteristics, treatment, and prognosis of primary pericardial mesothelioma (PPM). Methods The clinical,pathological and imaging data of 11 PPM patients diagnosed in Peking Union Medical College Hospital from 2014 to 2024 were retrospectively collected,the Kaplan-Meier curve was calculated by Log-Rank test to determine the prognostic factors of the patients. Results The median age of the 11 patients was 48 years, including one well-differentiated papillary mesothelioma, and ten malignant mesothelioma. CA125 was elevated in all patients. PET/CT all indicated increased pericardial metabolism. Male patients and patients with ECOG score ＞2 points had worse prognosis (P=0.018, P=0.01, respectively). Compared with the untreated group(4 cases), both immunotherapy(3 cases) and chemotherapy(3 cases) can prolong patient survival (P=0.025, P=0.025, respectively), and the benefit of immunotherapy was greater than chemotherapy (P=0.049 9). Conclusions This study is the largest single center pericardial mesothelioma cohort in China. CA125 and PET/CT contributes to the diagnosis of PPM, and immunotherapy might be the future direction of PPM treatment.

Key words: primary pericardial mesothelioma, diagnosis, immunotherapy, prognosis