[Primary cardiac angiosarcoma: a clinicopathological and molecular genetic analysis of thirteen cases]

Objective: To investigate the clinicopathological and molecular features of primary cardiac angiosarcoma (PCAS), and to analyze the correlation between KDR mutation and the clinicopathological features of PCAS. Methods: Thirteen cases of PCAS were collected at Beijing Anzhen Hospital, Capital Medical University from January 2007 to December 2021. The clinicopathological features, diagnosis, differential diagnosis and outcome were retrospectively analyzed. KDR mutation was detected by next-generation sequencing (NGS) and then the expression of KDR (VEGFR2) was determined by immunohistochemistry (IHC), with review of relevant literatures. Results: There were eight males and five females with a mean age of 45 years. The primary tumor was in the right atrium in 10 cases, left atrium in two cases and right ventricle in one case. The histomorphology was mainly poorly differentiated angiosarcoma (11 cases), with highly pleomorphic spindle or round cells in solid sheets, brisk mitotic activity and extensive necrosis. Vascular lumen formation was observed in two cases of high to moderate differentiation, and biphenotypic differentiation was seen in five cases. IHC staining showed CD34, CD31, Fli1, ERG and vimentin were diffusely positive, pan-cytokeratin was positive, Ki-67 index ranged from 3% to 90%, which was positively correlated with the differentiation degree and grade of the PCASs (P<0.05). At the end of follow-up period, one patient was alive, two patients were lost to follow-up, and the remaining 10 patients had an average survival time of 4.6 months. Finally, NGS sequencing was performed on seven samples after screening, and the results showed that KDR and NF1 mutations were both present in three cases. VEGFR2 expression had no significant correlation with the differentiation degree and grade of PCAS (P>0.05), and it was not related to KDR mutation. Conclusions: PCASs mainly occur in the right atrium, and are mainly poorly differentiated. Ki-67 index is helpful to assess the degree and grade of tumor differentiation. The occurrence and development of PCAS may be related to the pathway involved in KDR mutation, but KDR mutation has no clear correlation with clinicopathological characteristics of PCAS, and immunohistochemical staining can not replace gene detection to determine whether the tumor had KDR mutation.