[Nasal glial heterotopia: embryological and clinical approaches]

Nasal gliomas or heterotopia are nonhereditary congenital malformations composed of heterotopic neuroglial tissue. They usually present in infancy. Evaluation should include preoperative imaging with CT scan and/or MRI to rule out intracranial extension. There have been several cases reported in which nasal gliomas were misdiagnosed as capillary hemangiomas. The differential diagnosis includes prenasal space developmental impairment, which are nasoethmoidal meningoencephaloceles, nasal dermoid and epidermoid cysts.

We describe the case of a newborn male infant presenting at birth with a paramedial nasal glioma. An embryological and clinical analysis of nasal gliomas is proposed.

Nasal glioma is an uncommon congenital lesion presenting as a large panel of midline craniofacial anomalies. The embryological and anatomical origins of nasal gliomas are reviewed. The most known embryological theory was described by Grünwald in 1910 and is called the "prenasal space" theory. This theory is very attractive because of the embryopathogenic continuum proposed among dermoids, gliomas, and encephaloceles. In this article, we discuss major embryological theories on nasal gliomas pathogenesis and propose that while the prenasal space theory can explain the occurrence and the continuum between basal anterior or prenasal encephaloceles and gliomas, it cannot explain the occurrence of craniofacial demoids of the same topography. Better knowledge of embryological mechanisms implicated in the pathogenesis of nasal gliomas can help clinical management of this kind of malformations.