Primary malignant triton tumor of the heart: a case report and review of literature

Background: malignant triton tumor is a very rare malignant peripheral nerve sheath tumor (MPNST) with rhabdomyosarcomatous differentiation. In the present paper, we report aprimary malignant triton tumor in the heart of a 34-year-old woman who underwent resection of the left atrial tumor. To the best of our knowledge, this is the second case of primary malignant triton tumor of the heart reported in English. Case presentation: A 34-yearold woman underwent resection of the left atrial tumor. The tumor was fleshy white-tan, texture partial crisp and partially translucent. Histologically, the mass was composed of interlacingfascicles of hyperchromatic serpentine spindle cells. The cells had elongated and comma shaped nuclei and sparse cytoplasm with indistinct borders. Hypercellular and hypocellular zones with areas of palisading necrosis and myxoid stroma were also present. In the more myxoid areas, the parallel orientation of the cells was lacking. Large pleomorphic cells with abundant eosinophilic cytoplasm and rounded eccentric nuclei were seen admixed with neoplastic spindle cells. The pleomorphic cells were striated, strap-like, or globoid rhabdomyoblasts. Immunohistochemically, the tumor cells were positive for vimentin, NSE, weak expression S-100, and focally positive formyogenin, desmin, and MyoD1, negative for cytokeratin (pan), EMA, Actin (SM) and HMB-45. Conclusion: According to the morphological and immunohistochemical findings, we diagnosed this primary cardiac tumor as a primary malignant triton tumor. Heretofore, the experience of treating primary intracardiac malignant triton tumor is still lacking and more experience in diagnosis and treatment needs to accumulate.