Abstract

Cellular schwaninoma is a variant of schwannoma, which is characterized by predominance of cellular Antoni A area, presence of mitotic activity, nuclear hyperchromasia, pleomorphism, and absence of Verocay body. These pathologic features often prompted a misdiagnosis of malignancy. However, the clinical outcome has indicated the benignity of the tumor. We have experienced a case of cellular schwannoma arising from right facial nerve with right hemifacial weakness and erosion of mastoid process. Grossly, it was a 3.5 x 3 cm sized and relatively well encapsulated mass with yellowish, friable cut surface. Microscopically, cellular growth with moderate cellular pleomorphism and some mitotic activity (5/40 HPFS, up to 2/HPF) were noted. Immunostaining for S-100 protein showed diffuse strong positive reaction.

• Keywords: Cellular schwannoma;Facial nerve;S-100 protein;