Nasal glioma.

An 11-month-old girl had a congenital extracranial frontonasal glioma. The tumor was attached to the left membranous septum and excised by a simple ellipse and stalk dissection. The tumor is considered to arise from ectopic neuroectodermal tissue projected through the foramen cecum into the developing nasofrontal cranium and sequestered there on closure of the cranial sutures. Light microscopy demonstrated tumor tissue composed of fibrocollagenous septae separating interspersed glial cell islets and scattered hypoplastic skeletal muscle cells. Electron microscopy disclosed slender but differentiated muscle cells. No neuronal components could be identified. The heterotopic neuroglial nodules seemingly grew and differentiated by intermingling with either growing mesodermal cells or striated muscle cells or by transformation of some neuroglial elements into striated muscle cells. This extranasal glioma would best be classified as a benign congenital extranasal neuroectodermal tumor.