Organized cerebral heterotopia in the ethmoid sinus. A case report.

A 60-year-old woman afflicted with spontaneous CSF rhinorrhea was found to have a heterotopia consisting of well-differentiated neurons organized in layers in the lamina propria of the mucosa of the ethmoid sinus. This heterotopic cerebral anlage is best classified within the spectrum of "nasal gliomas". The origin of this malformation is a failure of closure of the anterior neuropore which delays the ingrowth of the mesoderm that is destined to form the skull and dura beyond the 10th week of gestation, leaving behind trapped cerebral tissue. The presentation of this congenital malformation late in life is attributed to the development of sinusitis.