Nasal glioma.

A congenital midline nasal mass is a rare anomaly usually detected at birth. The reported incidence is 1 in every 20,000 to 40,000 births. (1,2) The most common congenital nasal masses are nasal dermal sinus cysts, nasal encephaloceles, and nasal gliomas. These masses appear to share a similar embryogenic origin; they occur when the neuroectodermal and ectodermal tissues fail to separate during the development of the nose.

Neuroimaging is essential for identifying nasal lesions and for determining their exact location and possible intracranial extent. Treatment is surgical excision, and therefore preoperative knowledge of the mass' extent and possible intracranial connection or extension is a key element in surgical planning. (2)

The term nasal glioma is a misnomer because such a mass is not a true neoplasm; it is actually made up of ectopic nerve tissue that contains neuroglial elements, with glial cells in a connective tissue matrix with or without connection to the subarachnoid space or dura. (3) The male-to-female ratio is 3:2, and approximately 150 cases have been reported? No common association with other malformations and no familial predisposition have been described. Some cases of nasal glioma associated with other malformations, such as agenesis of the corpus callosum and cleft palate, have been reported. (4,5) Only 15% of all nasal gliomas communicate with the intracranial structures, usually at the level of the cribriform plate. (6) Nasal gliomas usually arise during infancy or later childhood. (7) They can be extranasal (60% of cases), lying external to the nasal bones and cavities; intranasal (30%), lying within the nasal cavity, mouth, or pterygopalatine fossa; or mixed (10%), communicating through a defect of the nasal bones? Other rare locations for heterotopic brain tissue include the lips, tongue, scalp, nasopharynx, and oropharynx. (9)

An intranasal glioma is usually attached to the upper part of the middle turbinate or to the nasal septum. Clinically, these masses are soft, pale, and polypoid. They can protrude through the nostrils and mimic a nasal polyp. Signs and symptoms include nasal obstruction, epistaxis, and cerebrospinal fluid (CSF) rhinorrhea. Nasal gliomas can be associated with deformities of the adjacent bones and obstruction of the nasolacrimal duct. A large mass can lead to hypertelorism, broadening of the nasal bridge, airway obstruction, and epiphora. (10,11)

Ninety percent of reported nasal gliomas do not contain neurons, possibly because of the low levels of oxygen in the mass and the lack of differentiation from embryonic neuroectoderm. The benign nature of nasal gliomas is demonstrated by low proliferative activity. (8)

Neuroimaging is essential for the characterization of an intranasal glioma to determine its exact location and, more important, to exclude possible intracranial extension. (12)

Both computed tomography (CT) and magnetic resonance imaging (MRI) are used to evaluate these lesions. CT can demonstrate bony defects, and MRI can demonstrate the characteristics of the soft-tissue mass and its possible intracranial connection. On CT, the mass is usually isodense to brain tissue. Findings that suggest intracranial involvement are an enlarged foramen cecum or bifid crista galli. On MRI, the lesion is isointense to hypointense relative to gray matter on T1-weighted sequences and hyperintense on T2-weighted and protondensity sequences (figure). The advantages of MRI include multiplanar imaging, better soft-tissue contrast, and a lack of ionizing radiation, which is important because the pathology is located at the level of the orbit. (13) The demonstration of a lack of CSF around the lesion can help differentiate nasal gliomas from encephaloceles.

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The definitive treatment is complete surgical excision, which should be performed as soon as possible after diagnosis to avoid further distortion of the facial bones. The entire mass (and a fistulous tract, when present) must be removed in order to prevent recurrence. Intranasal lesions are approached via lateral rhinotomy or by endoscopic techniques.

References

(1.) Paller AS, Pensler JM, Tomita T. Nasal midline masses in infants and children. Dermoids, encephaloceles, and gliomas. Arch Dermatol 1991;127:362-6.

(2.) Harley EH. Pediatric congenital nasal masses. Ear Nose Throat J 1991;70:28-32.

(3.) Lowe LH, Booth TN, Juglar JM, Rollins NK, Midface anomalies in children. Radiographics 2000;20:907-22.

(4.) Cerda-Nicolas M, Sanchez Fernandez de Sevilla C, Lopez-Gines C, et al. Nasal glioma or nasal glial heterotopia? Morphological, immunohistochemical and ultrastructural study of two eases. Clin Neuropathol 2002;21:66-71.

(5.) Uemura T, Yoshikawa A, Onizuka T, Hayashi T. Heterotopic nasopharyngeal brain tissue associated with cleft palate. Cleft Palate Craniofac J 1999;36:248-51.

(6.) Gorenstein A, Kern EB, Facer GW, Laws ER, Jr. Nasal gliomas. Arch Otolaryngol 1980;106:536-40.

(7.) Morgan DW, Evans JN. Developmental nasal anomalies. J Laryngol Otol 1990; 104:394-403.

(8.) Dimov P, Rouev P, Tenev K, et al. Endoscopic surgery for the removal of a nasal glioma: Case report. Otolaryngol Head Neck Surg 2001;124:690.

(9.) Kennard CD, Rasmussen JE. Congenital midline nasal masses: Diagnosis and management. J Dermatol Surg Oncol 1990;16: 1025-36.

(10.) Fitzpatrick E, Miller RH. Congenital midline nasal masses: Dermoids, gliomas, and encephaloceles. J La State Med Soc 1996;148:93-6.

(11.) Bradley PJ, Singh SD. Congenital nasal masses: Diagnosis and management. Clin Otolaryngol 1982;7:87-97.

(12.) Hoeger PH, Schaefer H, Ussmueller J, Helmke K. Nasal glioma presenting as capillary haemangioma. Eur J Pediatr 2001;160: 84-7.

(13.) Naidich TP, Airman NR, Braffman BH, et al. Cephaloceles and related malformations. AJNR Am J Neuroradiol 1992; 13:655-90.

From the Department of Radiology, Louisiana State University Health Sciences Center, New Orleans (Dr. Restrepo and Dr. Palacios), and the Department of Otorhinolaryngology, Universidad Javeriana, Bogota, Colombia (Dr. Martinez and Dr. Herrera).