Abstract

The pure epithelioid malignant schwanoma is a rare form of malignant schwanoma and differs from the ordinary epithelioid malignant schwanoma because of the absence of a spindle cell component. We present a case of purely epithelioid malignant schwanoma arising in the parapharyngeal area from vagus nerve without difinite evidence of von Recklinghausen's disease. The patient was a 28-year-old man with palpable right neck mass and swallowing difficulty during 2 years. The mass was an ovoid encapsulated tumor and measured 5x3x3 cm in dimension. The cut surface showed brownish tan homogeneous nodular appearance with partly myxoid area. Microscopically the tumor showed nodular pattern composed of epitheliod cells which were arranged in both tight clusters and stringy cords. The cells were ovoid in shape and had vesicular nuclei with single prominent eosinophilic nucleolei and sometimes abundant intracytoplasmic mucin. Mitoses were infrequent. Ultrastructural study showed rudimentary cell junction and degenerated cytoplasmic organelles including scattered mitochondriae, short segments of rough endoplasmic reticulum and lipid droplets. There were no definite basement membrane and melanosome. Immunohistochemical study showed the cells being positive for S100 protein, neuron specific enolase and myelin basic protein and negative for cytokeratin.