%0 Case Reports
%T Right atrial cardiac myxoma with malignant transformation to undifferentiated sarcoma: A case report.
%A Kaimori R
%A Nishida H
%A Oyama Y
%A Kusaba T
%A Kawamura K
%A Daa T
%J Cardiovasc Pathol
%V 73
%N 0
%D 2024 Jul 23
%M 39053747
%F 3.975
%R 10.1016/j.carpath.2024.107676
%X Generally, sarcomas arising from benign soft tissue are rare. Cardiac myxoma (CM) is a benign tumor, and few reports have described its malignant transformation. Herein, we documented a case of an 89-year-old man with prostate cancer and a 5-year history of a right atrium tumor without Carney complex. The tumor was resected surgically and had a myxomatous or gelatinous appearance. Microscopically, the tumor had two components: a sarcomatous area and myxomatous area. In the myxomatous area, typical myxoma cells were demonstrable and were strongly immunoreactive for immunohistochemistry (IHC) of calretinin. In the sarcomatous area, the epithelioid- to spindle-shaped cells with prominent atypia proliferated densely. The IHC profile of cells in the sarcomatous area was different from that of cells in the myxomatous area; MDM2-positive cells were found only in the sarcomatous area. Especially, the Ki-67 index and number of p53-positive cells in the sarcomatous area were higher than those in the myxomatous area. The transition of the two components was seamless. Thus, we made a diagnosis of CM with malignant transformation corresponding to undifferentiated pleomorphic sarcomas. This case suggests that CM may transform into sarcoma, albeit rarely.