Cardiac intracavitary metastasis of a malignant solitary fibrous tumor: case report and review of the literature on sarcomas with left intracavitary extension.
BACKGROUND
Solitary fibrous tumor (SFT) of the pleura with malignant progression occurs uncommonly. Cardiac intracavitary extension of tumors is rarely seen, with left side location being exceptional.


METHODS AND RESULTS
The authors report the first case of a malignant SFT metastatic to the heart occurring in a 74-year-old woman. The tumor first presented as a slow-growing pleural SFT that in 6 years reached a size of 16 cm. Two months after a complete surgical resection, the tumor was found to spread to the left atrium by intracavitary extension from the left upper pulmonary vein, simulating a cardiac myxoma. The primary tumor showed established features of malignancy including size greater than 10 cm; gross findings of necrosis; high cellularity, cytological atypia, and eight mitoses per 10 high-power fields. Immunohistochemical study revealed positivity of the tumor cells for CD34, bcl-2, and CD99. Aside from the present report, 52 previous cases of sarcoma with intracavitary extension to the left side of the heart have been described. Bone sarcoma is the type most frequently found. Peripheral arterial embolism can be a complication of advanced mesenchymal malignancy in 21% (11/53) of reported cases.


CONCLUSION
Accurate histopathologic recognition of this rare type of metastatic disease is important because of the adverse prognosis as compared to cardiac myxoma.