Solitary malignant schwannoma of the nasal cavity and paranasal sinuses: report of two rare cases.

Malignant schwannomas of the paranasal sinuses are extremely uncommon tumors, as only 18 well-documented cases have been previously published in the English-language literature. We report two new cases of solitary malignant schwannoma--one in a 23-year-old man and the other in a 45-year-old woman. Neither was associated with von Recklinghausen's disease. These tumors involved the maxillary sinus, nasal cavity, and orbit and extended intracranially. Following surgery, both patients experienced recurrences. The male patient developed a slowly enlarging intranasal mass at the same site 8 years following excision of the original tumor and postoperative radiotherapy. Microscopic examination of the recurrent tumor revealed that its features were similar histologically to those of the original. The female patient experienced a recurrence 1 year following her first operation.