A primary cardiac sarcoma with unusual histology and clinical course.

A left atrial tumor, in which radical resection was impossible, demonstrated two processes: An inflammatory pseudotumor and cellular atypia suggestive of a sarcoma. Immunohistochemistry (proliferating cell nuclear antigen [PCNA], MIB-1 [Ki-67 antibody], bcl-2 positive; p53 negative, focal loss of nm23) was supportive for a malignant tumor. Despite no further therapy because of uncertainty in tumor classification, the patient remained in remission for 28 months. Thereafter, spine metastases and local regrowth were found, and the patient died 15 months later, after temporary remission by radiotherapy. This case stresses the impact immunohistochemistry may have on diagnosis of malignancy and the difficulty in predicting the biological behavior of cardiac sarcomas.