咬筋内に発生した富細胞型神経鞘腫の１例

Abstract

Schwannoma is a benign tumor originating from Schwann's sheath. Cellular schwannoma is one of the variants of schwannoma, which differs from conventional schwannoma and is extremely rare in the oral and maxillofacial region. We present a case of cellular schwannoma arising in the masseter muscle. The patient was a 58-year-old woman who was referred to our hospital because of swelling of the left cheek. An elastic firm mass, 30mm in diameter, was found in the left cheek. The mass was movable and slightly tender. MRI revealed a well-circumscribed mass within the left masseter muscle. Under a clinical diagnosis of a tumor in the left cheek, the lesion was extirpated under general anesthesia. The tumor was encapsulated and easily removed. It was solid, and the cut surface was yellow. Histopathological examination revealed that the tumor consisted mainly of a proliferation of spindle cells resembling Schwann's cells with an Antoni A type pattern. Verocay bodies were not observed. High cellularity and mitotic activity were characteristic features. A small area with an Antoni B type pattern was also observed. Immunohistochemically, the tumor cells were positive for S-100. On the basis of these findings, the tumor was diagnosed to be a cellular sahwannoma. Recurrence has not been observed for 1 year 4 months after surgery.