Triton tumor of the parotid area. Case report.

A 27-year-old woman with a Malignant Triton Tumor (MTT), or malignant schwannoma with rhabdomyoblastic differentiation, located in the parotid cell and infiltrating the nasal sinuses and the left orbit is described. The initially resected tumor showed three recurrences within a 2 years follow-up period. During successive recurrences an increase in cellular density, number of mitoses and necrosis was noticed. Immunohistochemical analysis showed that the tumor was composed of a mixed population of cells. Some of them showed positivity for actin, desmin and myoglobin, while others were positive for S-100 protein, glial fibrillary acid protein, and IV-collagen. Cytokeratin stainings were negative. Up to now, 8 benign triton tumors and another 45 cases of MTT have been described. None of them was primarily located in the parotid gland, and infiltration to the orbital cavity has not been previously described.