Background: Distinguishing schwannoma from neurofibroma of the paranasal sinuses can be difficult.
Patients: We present the rare case of malignant peripheral nerve sheath tumor of the frontoethmoid complex that occurred in a patient who had suffered from schwannoma at the same site 7 years before. The tumor was examined clinically, histologically, and immunohistochemically.
Results: Although complete surgical excision of the primary tumor should have been an apparently adequate management for benign schwannoma, the tumor recurred and even metastasized into the brain. The tumor was resistant to aggressive surgical therapy combined with adjuvant irradiation and gamma knife therapy. The results of histological examinations identified schwannian features of the primary tumor and clearly outlined differentiation to solitary neurofibroma.
Conclusions: Considering that schwannomas can be predominantly benign with foci of malignant areas and that there are reported cases of malignant transformation of benign schwannomas, the present consensus in management of small and low-grade malignant schwannomas is complete surgical excision with negative margins. The therapy of choice for high-grade malignant schwannomas is aggressive surgical resection, with wide tumor free margins, combined with adjuvant irradiation and chemotherapy.