SCHWANNOMAS OF THE SINONASAL TRACT AND NASOPHARYNX

Approximately 45% of benign peripheral nerve sheath tumors occur in th e head and neck region. Of these, schwannomas (neurilemomas) arising f rom the nasal cavity and paranasal sinuses account for less than 4%. P athologic features of this subset are not well documented. We report a series of five cases of sinonasal schwannoma and one in the nasophary nx The male-to-female ratio was equal, and the age at presentation ran ged from 38 to 65 years of age (median, 52 yr). Four of the lesions we re located within the nasal cavity, one arose from the maxillary sinus , and one originated in the nasopharynx, with extension into the Eusta chian tube. Two cases showed local bony destruction, with intracranial extension. Presenting clinical symptoms included nasal obstruction, e pistaxis, rhinorrhea, anosmia, facial swelling, headache, and serous o titis media; the two cases with intracranial spread also presented wit h visual disturbances. All of the six cases were treated by surgical e xcision. Clinical follow-up in five cases ranged from 6 to 48 months ( median, 27 mo). Histologically, all of the lesions shared many cytomor phologic features common to schwannomas arising at other sites, and al l of the six cases showed strong, diffuse immunoreactivity for S-100 p rotein. Four cases showed features of the cellular variant, and one sh owed focal granular cell change. An unusual and previously poorly docu mented histologic feature, distinct from schwannomas arising at most o ther anatomic sites, was a lack of encapsulation, which, when combined with hypercellularity, often raised suspicion of malignancy. Because none of the cases in this series has shown either local recurrence or postoperative metastasis to date, lack of encapsulation and locally de structive growth in an otherwise histologically typical schwannoma ari sing at this site should not suggest malignant potential.