[Malignant peripheral nerve sheath tumor with divergent cartilage differentiation from the acoustic nerve: case report].

Malignant peripheral nerve sheath tumors(MPNSTs) of the acoustic nerve are very rare. Only seven cases of MPNST arising from the acoustic nerve have been reported. The authors present a case of MPNST with divergent cartilage and melanotic differentiation of the acoustic nerve. The patient was a 69 year old man admitted to our neurosurgical service in January 1999 complaining of left facial nerve palsy and hearing difficulty of his left ear. The initial CT showed a tumor at the left cerebellopontine angle region. On MRI the tumor was depicted as low intensity on T 1-weighted image and high intensity on T 2-weighted image, the mass was heterogeneously enhanced after administration of Gd-DTPA. The partial removal of the tumor was performed in January 1999. He was discharged February 1999. But he was admitted again because of progressive cerebellar ataxia. MRI showed the rapid regrowth of the residual tumor. In March 1999, complete removal of the tumor was performed. Histopathological analysis revealed a malignant spindle cell neoplasm with divergent cartilage and melanotic differentiation. We review the relevant literature concerning MPNST of the acoustic nerve and discuss the clinical features of malignant eighth cranial nerve tumor.