Nasal cavity, paranasal sinuses, nasopharynx

Other nonneoplastic lesions

Glial heterotopia



Last author update: 2 February 2024
Last staff update: 2 February 2024

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PubMed Search: Glial heterotopia

Saira Javeed, M.B.B.S., M.Phil.
Nasir Ud Din, M.B.B.S.
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Cite this page: Javeed S, Qureshi MB, Ud Din N. Glial heterotopia. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/nasalglialheterotopia.html. Accessed April 14th, 2024.
Definition / general
Essential features
Terminology
  • Acceptable: ectopic glial - meningeal tissue, neuroglial heterotopia, nasal glial heterotopia, nasal glioma
  • Not recommended: heterotopic brain choristoma, ectopic brain tissue
ICD coding
  • ICD-10: Q30.8 - other congenital malformations of nose
  • ICD-11: LA70.Y - other specified structural developmental anomalies of the nose or cavum
Epidemiology
Sites
Pathophysiology
  • Congenital, nonhereditary malformation
  • Development of nasal cerebral heterotopia is embryologically similar to that of nasal encephalocele or dermoid
  • During retraction of the embryonic dural diverticulum, remnants of neural glial tissue become sequestered when their connections to the subarachnoid space are pinched off and obliterated
  • Lack of subarachnoid communication distinguishes heterotopia from anterior encephalocele
  • Distinction between glioma and encephalocele is not possible based on histopathologic findings because glial tissue may be the predominant or exclusive component in both types of lesions (Acta Otorhinolaryngol Ital 2022;42:317)
Etiology
Clinical features
Diagnosis
  • Diagnosis requires strong clinical and radiologic correlation in addition to histology of lesion
  • Magnetic resonance imaging (MRI) to exclude communication with the central nervous system and plan a surgical approach
  • Additional computed tomography (CT) performed if bony involvement is suspected or necessary for endoscopic surgery (Acta Otorhinolaryngol Ital 2022;42:317)
Radiology description
  • Radiology is necessary to determine the location of the mass and its relationship to the skull base
  • MRI characteristics of glial heterotopia resemble normal brain tissue in all pulse sequences
  • Cystic elements might be present and represent cerebrospinal fluid (CSF)-like fluid filled spaces
  • MRI findings (J Cutan Aesthet Surg 2020;13:233, Acta Otorhinolaryngol Ital 2022;42:317)
    • Circumscribed, ovoid soft tissue intensity lesion
    • Isointense signal in T1 weighted imaging
    • Heterogeneously hyperintense signal in T2 weighted imaging
    • Moderate enhancement postintravenous gadolinium contrast
    • No connection between the mass and the dura or brain
  • Noncontrast computed tomography (NCCT): soft tissue density, space occupying lesion with no communication with nasal cavity or brain (J Cutan Aesthet Surg 2020;13:233)
Radiology images

Contributed by Nasir Ud Din, M.B.B.S.
Nasal swelling

Nasal swelling

Nasal cavity lesion

Nasal cavity lesion

Nasal cavity mass

Nasal cavity mass

Prognostic factors
  • Benign lesion with good prognosis (Int J Pediatr Otorhinolaryngol 2020;129:109728)
  • Local recurrence rate: up to 30% with incomplete excision
  • Histological evaluation of surgical margins can reduce the risk of recurrence
  • Most recurrences occur within the first 12 months
Case reports
Treatment
Clinical images

Images hosted on other servers:
External nasal lesion with skin tightening

External nasal lesion with skin tightening

Globular swelling at the root of nose

Globular swelling at the root of nose

Nasal endoscopy

Nasal endoscopy

Gross description
  • Size range: 1 - 3 cm; can grow up to 7 cm
  • Firm, globular to polypoidal smooth mass with homogenous gray to pearly white cut surface (J Cutan Aesthet Surg 2020;13:233)
  • Grows slowly in proportion to adjacent tissue
Gross images

Images hosted on other servers:
Homogeneous, tan, firm cut surface

Homogeneous, tan, firm cut surface

Microscopic (histologic) description
  • Nonencapsulated lesion with ill defined edges
  • Composed of variable sized mats and nests of benign and mature brain tissue in a background of vascularized connective tissue
  • Histologically, brain tissue shows a predominant glial component and minimal neuronal component if present
  • Glial component shows evenly dispersed astrocytes in a fine, neurofibrillary matrix
  • Interspersed large gemistocytes, ependyma, choroid plexus, retinal epithelium, cerebellar tissue and leptomeninges may be present (J Cutan Aesthet Surg 2020;13:233)
  • Rare proliferation of eccrine ducts
  • Longstanding lesions show fibrosis and collagen
  • Large amount of fibrotic tissue can undermine the glial tissue in H&E sections
  • Inflammation, focal calcification may be seen
  • Mitoses are absent
Microscopic (histologic) images

Contributed by Nasir Ud Din, M.B.B.S.
Polypoid lesion

Polypoid lesion

Syncytial architecture

Syncytial architecture

Nested architecture

Nested architecture

Astrocytes in fibrillary matrix

Astrocytes in fibrillary matrix

Astrocyte morphology

Astrocyte morphology


Astrocytes in mild inflammatory stroma

Astrocytes in mild inflammatory stroma

Vascularized background

Vascularized background

Fibrotic appearance

Fibrotic appearance

Positive GFAP expression

Positive GFAP expression

Positive stains
Molecular / cytogenetics description
  • Not required for routine diagnosis
  • Copy number profiling from global DNA methylation data showed a balanced genome
  • One case showed significant copy number variation involving loss of chromosomes 16, 17 and 19 and gain of chromosomes 4 and 5 (Childs Nerv Syst 2022;38:63)
Sample pathology report
  • Nasal swelling, excision:
    • Glial heterotopia, intranasal type (see comment)
    • Resection margin is free
    • Comment: The tissue shows respiratory epithelium covered unencapsulated polypoid lesion with poorly defined borders. The lesion is composed of nests and patches of mature glial tissue showing evenly dispersed astrocytes in a fine, neurofibrillary matrix. Mitosis is absent. Based on combined radiologic features and histologic findings, the lesion is best characterized as nasal glial heterotopia. This lesion is typically benign with recurrence associated with incomplete excision.
Differential diagnosis
  • True encephalocele:
    • Extracranial hernias of the meninges or brain caused by congenital defects in the skull
    • Intracranial connection present (Medicine (Baltimore) 2018;97:e12000)
    • Histologically similar to heterotopia; imaging required for correlation
    • Due to shared molecular alterations in a subset of nasal glial heterotopia and encephalocele, there is a strong suggestion that these 2 entities represent the same histopathologic entity (Childs Nerv Syst 2022;38:63)
  • Teratoma:
    • Congenital or developmental tumor derived from multipotent cells
    • Extremely rare (2%) in head and neck region (Int J Pediatr Otorhinolaryngol 2015;79:1991)
    • May present as a congenital nasal midline mass
    • Differentiate into diverse types of tissue derived from the 3 germ layers (Chest 2005;128:2893)
    • Histology shows derivatives of germ layers in variable combination
    • Mature type contains neural tissue, teeth, skin, hair, fat, bone, cartilage, respiratory or intestinal epithelium
    • Immature type has additional primitive neuroepithelium with rosettes, pseudorosettes or neurofibrillary matrix in some tumors (Iran J Otorhinolaryngol 2018;30:355)
  • Neurofibroma:
    • Neural tumor occurs in second or third decades of life
    • Wide anatomic distribution but diffuse type neurofibromas usually arise in the head and neck region
    • Histology shows spindle cells with wavy, tapering nuclei arranged haphazardly or in fascicles
    • Stroma shows collagenous (shredded carrot collagen or homogeneous pink) rather than fibrillary appearance
    • CD34 positive
  • Ectopic meningioma / meningothelial hamartoma:
    • Meningothelial neoplasm arises in children and young adults
    • Usually occurs in the head and neck
    • Histology shows syncytial lobules and whorls of spindle cells with regular nuclei and pale intranuclear cytoplasmic inclusions
    • May show psammomatous calcifications
    • Meningothelial hamartoma arises in infants; most common site is posterior scalp
    • Shows slit-like pseudovascular spaces lined by spindle cells along with small clusters in a fibrocollagenous stroma
    • EMA positive
  • Congenital hemangioma:
    • Benign vascular tumor, fully developed at birth (BMJ Paediatr Open 2020;4:e000816)
    • Superficial, occurs commonly in head and neck region
    • Have similar clinical presentations as heterotopia
    • Usually presents as a reddish purple limited lesion covered with fine or coarse telangiectasia
    • Frequently shows a pale peripheral halo (BMJ Paediatr Open 2020;4:e000816)
    • Prenatal ultrasound diagnosis between nasal glial heterotopia and congenital hemangioma is difficult
    • Fetal MRI is not very specific for distinguishing between the 2 lesions but excludes the presence of an intracerebral connection in case of heterotopia
    • Postnatal exams are more specific (J Stomatol Oral Maxillofac Surg 2017;118:298)
    • Histology shows poorly canalized vessels and mitotically active endothelium in rapid growth phase
    • Lumina become prominent with maturation and a combination of solid and vascular areas in varying proportions may be seen
  • Ganglioglioma:
    • Glioneuronal tumor that makes up ~2% of all primary intracranial tumors (Childs Nerv Syst 2016;32:1839)
    • Predilection for children and young adults (median age: 12 years)
    • Mostly occurs in temporal lobe
    • Histology shows biphasic tumor with variable mixture of mature appearing ganglion-like cells and atypical glial cells
    • Large ganglion-like cells may show bi or multinucleation
    • Atypical glial cells show moderate enlargement with hyperchromasia and mimic those of fibrillary astrocytomas, pilocytic astrocytoma or oligodendroglioma
    • May show perivascular lymphocytic cuffing, eosinophilic granular bodies and dystrophic calcifications (Childs Nerv Syst 2022;38:63)
Board review style question #1

A 6 month old infant presented with swelling in the nose since birth. Radiology showed a well circumscribed lesion with no connection to brain or dura. Histological examination revealed nests of glial tissue embedded in a fibrillary stroma. Which immunostain will be most likely expressed by the lesional cells?

  1. CD34
  2. Desmin
  3. EMA
  4. GFAP
  5. SMA
Board review style answer #1
D. GFAP. The glial tissue will be immunopositive for GFAP (J Cutan Aesthet Surg 2020;13:233, Br J Ophthalmol 1993;77:817). Answer A is incorrect because CD34 is a vascular marker and also shows positive expression in some fibrohistiocytic lesions. Answer B is incorrect because desmin is a myogenic marker expressed in skeletal muscle and smooth muscle lesions. Answer C is incorrect because EMA is positive in meningeal and epithelial cells (Oncol Lett 2013;5:768, J Oral Maxillofac Pathol 2023;27:604). Answer E is incorrect because SMA is expressed in smooth muscle cells and myofibroblasts in normal, reactive or neoplastic tissue.

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Reference: Glial heterotopia
Board review style question #2

A 2 year old child underwent surgical resection of a nasal mass. The histology was consistent with nasal glial heterotopia. What is the possible behavior of this lesion?

  1. Benign
  2. Intermediate, locally aggressive
  3. Intermediate, rarely metastasizing
  4. Malignant
  5. Uncertain potential
Board review style answer #2
A. Benign. Nasal glial heterotopia is a benign lesion with a very good prognosis. Recurrence rate is low and related to incomplete excision (Int J Pediatr Otorhinolaryngol 2020;129:109728). Answers B - E are incorrect because the lesion does not show intermediate or malignant features.

Comment Here

Reference: Glial heterotopia
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