Pedunculated nasal glioma: MRI features and review of the literature.

J Shah, D Patkar, T Patankar, A Krishnan, S Prasad, J Limdi 
 Department of Radiology, Dr Balabhai Nanavati Hospital, Vile Parle, Mumbai, India., India

Correspondence Address:
J Shah
Department of Radiology, Dr Balabhai Nanavati Hospital, Vile Parle, Mumbai, India.
India

Full Text

Nasal gliomas are uncommon lesions; with approximately 100 cases reported in the literature[1],[2]. The presence of a pedicle is almost always seen in encephaloceles and is rare in nasal gliomas. A case of intranasal glioma with a pedicle is reported.

::   Case report

A one-month-old newborn infant presented difficulty in breathing since birth. The mother had noticed an increased distance between both the medial canthi. Clinical examination revealed a reddish, polypoidal mass medial to the middle turbinate in the left nasal cavity. It did not reveal any translucency or pulsations. No changes were noted in the size of the lesion after compression of the left-sided jugular veins. Magnetic resonance imaging (MRI) revealed a relatively homogeneous intranasal mass in the left nasal cavity causing displacement of the left middle turbinate and nasal septum laterally. It appeared iso- to mildly hypointense on T1WI and hyperintense on PD and T2WI to the grey matter. Superiorly, an isointense pedicle was seen, which connected this mass to the intracranial contents through a defect in the cribriform plate. No obvious sac like structure was seen surrounding this mass. The mass was surgically removed with reconstitution of the dura. Histopathology of the specimen revealed a mixture of neuroglial and fibrovascular tissue with mature glial fibrillary acidic protein - positive astrocytes within the neuralgia, consistent with the diagnosis of glioma. No cellular atypia or abnormal mitoses was seen.

::   Discussion

Congenital midline nasal masses are rare anomalies, occurring one in 20,000-40,000 live births. According to the present widely accepted theory, nasal gliomas, dermal sinuses and encephaloceles result from incomplete regression of the dura that transiently traverses the prenasal space. Dermoids and epidermoids result from desquamation of cells of the dermis and epidermis lining the tract[3],[4],[5].

Nasal gliomas occur sporadically with no familial tendency or sex predilection[2]. Usually these are isolated anomalies without any other congenital malformations in the rest of the body. These are benign masses of glial tissue, occurring near the root of the nose and are not covered by any cerebrospinal fluid (CSF)-filled space which may be in connection with the subarachnoid space or ventricles of the brain (as in skull base cephaloceles or encephaloceles)[6],[7],[8]. Only in 15% of the cases, nasal gliomas remain connected with the intracranial structures by, a pedicle of glial tissue, usually through a defect in the cribriform plate[2].

Nasal gliomas can be extranasal (60% lying external to the nasal bones and nasal cavities), intranasal (30% lying within the nasal cavities, mouth or rarely in the pterigo-palatine fossa) or mixed (10% with both intra and extra nasal components communicating via a defect in the nasal bones or around its edges)[7],[2].

The usual age of presentation of the nasal gliomas is in infancy or early childhood. It does not show any change in size following compression of the ipsilateral jugular veins (negative Fursteinberg sign) or after crying (Valsalva's manoeuvre)[2],[9]. Nasal gliomas can cause remodelling and deformities of the adjacent bones and commonly cause hypertelorism. Obstruction of the nasal passage and nasolacrimal duct can lead to respiratory distress and epiphora on the affected side. Complications like CSF rhinorrhoea, meningitis or epistaxis can also develop in these patients[7].

Nasal gliomas are classified as heterotopias and not as neoplasia since pathologically they resemble reactive gliosis. They present as a firm, skin covered, reddish coloured, non-pulsatile, usually slowly growing, polypoidal lesions. No microscopic invasion, mitotic figures or metastases have been reported so far. They usually contain large aggregates of astrocytes (fibrous or gemistocytic) and fibrous connective tissue enveloping the blood vessels. About 90% of the reported nasal gliomas do not contain neurones, explained by either insufficient supply of oxygen to support the neurons or failure of the neurons to differentiate from the embryonic neuroectoderm in an intranasal glioma or both[7],[9].

Nasal gliomas are usually isodense on CT Scan. They can deform the bones of the nasal fossa and may have extensions through the glabella, nasal bones, cribriform plate or the foramen cecum. Calcifications are rarely reported in them[6]. Cystic changes may occasionally, occur within them. They may protrude out of the nostril and rarely attach to the nasal septum.

Imaging studies may differentiate nasal glioma from encephalocele if an adjacent communicating CSF space is present, to suggest cephalocele or an encephalocele. CT cisternography may occasionally be required to show adjacent CSF space. On MRI, nasal gliomas are usually hyperintense on T2WI. They may appear hypo-, iso- or hyper-intense to the grey matter on T1WI. Adjacent CSF space may be shown by MRI in encephaloceles [10],[11]. Encephaloceles usually retain connection with the brain parenchyma whereas nasal gliomas do not. Using MRI, nasal dermoids (which appear strikingly hyperintense on T1WI due to fat content) and epidermoids (which appear marginally hyperintense to the CSF on both T1 and T2WI) can easily be differentiated from nasal gliomas. These are almost always associated with dermal sinus tracts, but the full extent of this may be difficult to delineate with imaging studies[10]. Other less common causes of intranasal mass lesions in an infant include inclusion cysts. haemangiomas and aberrant ethmoid sinuses[10]. Unlike inflammatory polyps, nasal gliomas typically lie medial to the middle turbinate, occur in infancy, are less translucent and firm in consistency. Inflammatory polyps usually lie inferolateral to the middle turbinate. Contrast scans can help in detecting basal exudates and areas of encephalities in complicated cases[1],[10],[11]. In conclusion, in an infant presenting with a mass lesion in the nasal cavity with typical clinical and imaging findings, the possibility of nasal glioma should be strongly considered. Presence of a pedicle does not necessarily exclude a nasal glioma.

References