Nasal glial heterotopia: a clinicopathologic and immunophenotypic analysis of 10 cases with a review of the literature.

Nasal glial heterotopia (also known as "nasal glioma"), is a rare developmental abnormality seen in a wide age group but typically presenting at birth or in early childhood. Failure to recognize the entity is the principle difficulty in diagnosis. Ten cases of nasal glial heterotopic diagnosed between 1970 and 2000 were identified. Histologic and immunohistochemical features were evaluated and patient follow-up was obtained. The patients included five females and five males with a mean age at presentation of 8.6 years (range, birth to 44 years). Most patients presented clinically with a polypoid mass in the nasal cavity, although two patients had a mass on the nasal bridge. Symptoms were present for an average of 2 to 3 months. A connection to the central nervous system was identified in one case. Masses ranged in size from 1 to 7 cm in greatest dimension (mean, 2.4 cm). Histologically, the masses were composed of astrocytes (including gemistocytic type) and neuroglial fibers intermixed with a fibrovascular connective tissue stroma. Neurons and ependymal cells were noted in two cases. Focal calcifications and inflammatory cells were identified occasionally. Masson trichrome stains the collagen intensely blue, while the neural population stains magenta. Immunohistochemical reactivity with glial fibrillary acidic protein and S-100 protein will help to confirm the histologic diagnosis, while collagen type IV and laminin can highlight the reactive fibrosis. All cases were managed by surgery. All patients were alive without complications at last follow-up (mean, 26.8 years), except for the single fetus included in the study. Nasal glial heterotopia typically involves the nasal cavity and usually presents perinatally, although three patients presented in adulthood. The subtle glial component on routine microscopy can be accentuated with a trichrome stain or by immunoreactivity with glial fibrillary acidic protein and S-100 protein. Imaging studies must be performed before surgery to exclude an encephalocele, which requires different surgery. Complete surgical excision of nasal glial heterotopias is curative.