Malignant peripheral nerve sheath tumors of the head and neck: two cases and a review of the literature.

Malignant peripheral nerve sheath tumors are uncommon lesions that occasionally affect the head and neck. We describe 2 new cases of head and neck pathology. One tumor involved the parotid gland and resulted in erosion of the temporal bone, and the other affected the lower lip. A rapid diagnosis has significant implications for management because of the tumor's potential for aggressive behavior and its high rate of recurrence. To the best of our knowledge, lip involvement is rare and temporal bone involvement has not been previously described.