Primitive neuroectodermal tumor of the myocardium: a case report, review of the literature, immunohistochemical, and ultrastructural study.

We report the case of a primitive neuroectodermal tumor (PNET) arising in the heart of a 63-year-old man. The neuroectodermal nature of this tumor was confirmed by the immunohistochemical positivity for O13 (CD99) (the P30/32MIC2 gene product) neuron specific enolase (monoclonal and polyclonal), synaptophysin and vimentin. Other markers, such as actin, desmin, myoglobin, chromogranin, keratin, and leukocyte common antigen were negative. The diagnosis was made on an endomyocardial biopsy and was confirmed in sections from the myocardial tumor found within the heart excised during cardiac transplant. Primitive neuroectodermal tumors have been reported in a variety of sites, most commonly in the extremities. No case has ever been reported within the myocardium, although one has been reported in the pericardium. In addition to morphological similarities, PNET and extraskeletal Ewing's sarcoma have been shown to possess the same chromosomal translocation, t11;22, and the same cell surface antigen, P 30/32. Separation of this case from extraskeletal Ewing's sarcoma was possible because of the absence of PAS positivity, as well as the immunohistochemical positivity for at least two neural markers, as extraskeletal Ewing's sarcoma is only positive for neuron specific enolase.