Atypical and low-grade malignant vestibular schwannomas: clinical implications of proliferative activity.

OBJECTIVE: To examine the relationship between histopathology, immunohistochemistry, and clinical behavior in atypical and low-grade malignant vestibular schwannomas. STUDY DESIGN: The study design was a retrospective case review in conjunction with a histopathologic and immunohistochemical proliferation marker study of archival specimens. DATA SOURCES: A tertiary referral center's anatomic pathology and vestibular schwannoma computerized databases. METHODS: The diagnosis of atypical or low-grade malignant vestibular schwannoma was based on the number of mitotic figures present per tumor slide. MIB1 labeling indices were used to compare the proliferative activity of the atypical and low-grade malignant groups with that in an age-matched and size-matched control group. RESULTS: Eight cases of atypical and six cases of low-grade malignant vestibular schwannoma were diagnosed from 1990 to 1998. In the atypical and low-grade malignant groups, respectively, the average patient age was 54.3 years (range, 38-74 yr) and 50 years (range, 38-72 yr), and the average total tumor size was 1.53 cm (range, 0.7-3.5 cm) and 1.55 cm (range, 1.5-2 cm). Two recurrences were identified from the low-grade malignant group, and there was one postoperative House-Brackmann Grade III facial weakness. There were no recurrences or facial palsies in the atypical group. No distant metastasis or aggressive local invasion was observed in either group. MIB1 labeling indices were significantly (p < or = 0.001) higher in the atypical (4.69%) and low-grade malignant (5.23%) groups than in the control group (1.99%). CONCLUSIONS: These findings suggest a tendency for recurrence in proliferative tumors; however, the designation of malignancy should be reconsidered.

Histopathologic evaluation of the ethmoid bone in chronic sinusitis.

Chronic rhinosinusitis (CRS) is defined as a condition lasting for a period greater than 12 weeks, and manifested by an inflammatory response involving the mucous membranes of the nasal cavity and paranasal sinuses, fluids within these cavities, and/or the underlying bone. The mucosal changes that occur in CRS have been well described, and include edema, decreased number of ciliated cells, and goblet cell hyperplasia. However, the changes that may occur in the underlying ethmoid bone have only recently been investigated. We evaluated decalcified ethmoid bone specimens from 20 patients undergoing endoscopic sinus surgery for CRS. Our analysis revealed histopathologic changes consistent with varying grades of bone remodeling. Polarized light microscopy demonstrated changes in the extracellular matrix, such as bone resorption and neoosteogenesis. Preoperative clinical data and CT staging were recorded on all patients and correlated with the histopathologic findings. These findings suggest that CRS may be associated with osteitis of the underlying ethmoid bone.