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Parapharyngeal neuroglial heterotopia extending through the skull base in a neonate with airway obstruction
Journal of Pediatric Surgery (2007) 42, 1764–1767
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Parapharyngeal neuroglial heterotopia extending through the skull base in a neonate with airway obstruction Thierry A.G.M. Huisman a,⁎, Ulrike Brehmer a , Georg Zeilinger b , Thomas Stallmach c , Claudine Gysin d a
Department of Diagnostic Imaging, University Hospital Zurich, CH-8032 Zurich, Switzerland Department of Neonatology, Kantonsspital Aarau, CH-5001 Aarau, Switzerland c Department of Pathology, University Hospital Zurich, CH-8032 Zurich, Switzerland d Department of Surgery, University Children's Hospital Zurich, CH-8032 Zurich, Switzerland b
Index words: Heterotopic brain tissue; Parapharyngeal; MRI
Abstract We present a neonate with heterotopic nasopharyngeal brain tissue causing airway obstruction. Preoperative imaging showed extension of the mass along major neurovascular pathways into the cranial vault. Preoperative identification of intracranial extension is essential for planning surgery to prevent postoperative cerebrospinal fluid leaks or possible meningitis. © 2007 Elsevier Inc. All rights reserved.
Parapharyngeal masses in the neonate are rare and may cause airway obstruction. The differential diagnosis includes a variety of lesions such as cystic hygroma, hemangioma, glioma, encephalocele, meningocele, teratoma, branchial cleft anomaly, neurofibroma, and sarcoma [1,2]. Heterotopic parapharyngeal neuroglial tissue or heterotopic parapharyngeal brain tissue is a rare finding [1,2]. These lesions are composed of differentiated neuroectodermal derivates such as neurons, astrocytes, ependymal cells, and choroid plexus. They may be cystic because of the production of a fluid that resembles cerebrospinal fluid (CSF). By definition, there should be no continuity or communication with the cranial vault and its contents [3]. We report on a term neonate who presented with airway obstruction owing to parapharyngeal neuroglial heterotopia
⁎ Corresponding author. Tel.: +41 44 266 7110; fax: +41 44 266 7161. E-mail address: [email protected] (T.A.G.M. Huisman). 0022-3468/$ – see front matter © 2007 Elsevier Inc. All rights reserved. doi:10.1016/j.jpedsurg.2007.06.014
that extended through the skull base into the cavernous sinus and Meckel cave.
1. Case report We report on a term neonate who presented with an obstructed nasal respiration and a significant inspiratory and expiratory stridor. Symptoms aggravated in the supine position. On day 5 of life, endoscopy revealed a large epipharyngeal mass protruding into the oropharynx with infiltration of the soft palate. In addition, a mild laryngomalacia was noted. Tumor biopsy was performed. Histologic findings were nonconclusive. Magnetic resonance imaging (MRI) showed a large, T1 and T2 heterogeneous, partially cystic, partially solid tumor within the right parapharyngeal space (Fig. 1A and B). The tumor extended into the masticator space, the pterygopalatine fossa, and along the internal carotid artery into the cavernous sinus. In addition,
Parapharyngeal neuroglial heterotopia
1765
Fig. 1 A, Coronal T2-weighted fast spin-echo (FSE) magnetic resonance images. The heterotopic brain tissue presents as an inhomogeneous, partially hyperintense, partially hypointense lesion within the right parapharyngeal space (left image, arrows). Hypointense, solid components extend along the carotid artery and the maxillary nerve into the right cavernous sinus (middle and right images, arrows). B, Axial T2-weighted FSE magnetic resonance images. The left parapharyngeal component is moderately hyperintense (arrows) and displaces the right parotid gland laterally and the pterygoid muscles anteriorly. The mass also extends into the right cavernous sinus and inferior orbital fissure (arrowheads). The parapharyngeal component is partially isointense to the brain parenchyma.
the tumor reached Meckel cave through the foramen rotundum (Fig. 1A and B). The skull base was unremarkable; no bony defects were seen. The brain was without abnormality. Subsequently, a subtotal tumor resection was achieved using a lateral approach. Histologic analysis of the tumor showed mature neuroglial tissue, ependymal cells, and choroid plexus elements. The neuroglial tissue showed a positive immunohistochemical expression of glial fibrillary acid protein. No meningeal structures were identified. The tumor location in combination with the histologic and MRI findings led to the diagnosis of a parapharyngeal neuroglial heterotopia. The girl recovered well from surgery. Persisting swallowing problems required placement of a percutaneous gastric tube. The child developed well 1 year after surgery. Follow-up MRI showed stable residual tumor tissue within the parapharyngeal space (Fig. 2A and B).
2. Discussion Heterotopic neuroglial tissue or heterotopic brain is a rare anomaly composed of differentiated derivates of the
neuroectoderm outside the cranial vault or spinal canal and without communication with the brain, spinal cord, or meninges [1-3]. Brain heterotopia is most frequently seen in the nasal cavity. Rarely, heterotopia has been reported in the scalp, orbit, pterygopalatine fossa, pharynx, palate, lips, tongue, middle ear, and neck [1-3]. Patients usually present in the neonatal period with airway obstruction, swallowing difficulties, or a focal neck swelling. Heterotopic neuroglial tissue within the pharynx should be differentiated from skull base meningoencephaloceles and nasal gliomas. The surgical approach and technique as well as the possible complications differ, however, significantly. Preoperative imaging should characterize and localize the lesion. In particular, an intracranial extension should be excluded. Meningoencephaloceles will show a direct communication through a skull base defect with the cranial vault. Nasal gliomas contain glial cells; they lack, however, more complex elements such as neurons, ependymal-lined structures, or functioning choroid plexus tissue [1]. Consequently, they will have a more homogeneous appearance and signal intensity on MRI. The pathogenesis of heterotopic brain tissue is not yet fully understood. Several theories have been proposed
1766
T.A.G.M. Huisman et al.
Fig. 2 A, Postoperative follow-up axial T2-weighted FSE magnetic resonance images. A residual component is seen within the right parapharyngeal and infratemporal space (arrows). The anterior component is cystic in nature. Unchanged appearance of the solid components within the right cavernous sinus and inferior orbital fissure (arrowheads). B, Coronal T1-weighted magnetic resonance images. The cystic parapharyngeal component is T1 hypointense and CSF isointense (arrows). The solid component that extends into the cavernous sinus is T1 hypointense and isointense to the brain parenchyma (arrowhead). The right foramen rotundum lacks the hyperintense perineural fat tissue and is consequently hypointense compared with the left side (slim arrows).
including (a) encephaloceles that lost their cranial connection during development of the skull base, (b) displaced totipotent neuroectodermal cells that developed into mature neural tissue, and (c) entrapment of erroneously migrated olfactory bulb glial cells [1,3]. Currently the encephalocele theory is most widely accepted [3]. Imaging is essential to localize and characterize the lesion. Computed tomography and MRI are complementary imaging modalities. The high soft tissue resolution of MRI is especially helpful to localize and characterize the lesion. Computed tomography is advantageous because it may show osseous complications such as erosion of the adjacent skull base, mandible, or pterygoid plates. Reviewing the literature, we found that the key feature of heterotopic parapharyngeal brain heterotopia is the lack of an
extension into the cranial vault. Giannas et al [3] discussed, however, that there is a theoretical possibility of an intracranial communication of the heterotopic brain tissue. This could potentially lead to a CSF leak after surgery. Our case is of importance because this intracranial extension was identified by preoperative MRI. The lesion extended into the cavernous sinus along the internal carotid artery and reached the Meckel cave along the maxillary nerve. Magnetic resonance imaging had ruled out a meningoencephalocele. In addition, MRI had ruled out coexisting brain anomalies. In conclusion, our case demonstrates that heterotopic parapharyngeal brain tissue may extend into the cranial vault following neurovascular pathways. Consequently, preoperative imaging is mandatory to plan surgery in order to prevent CSF leaks.
Parapharyngeal neuroglial heterotopia
References [1] Behar PM, Muller S, Gerber ME, et al. Heterotopic neuroglial tissue causing airway obstruction in the newborn. Arch Otolaryngol Head Neck Surg 2001;127:997-1002.
1767 [2] Chen CY, Huang JH, Choi WM, et al. Parapharyngeal neuroglial heterotopia presenting as a growing single locular cyst: MR imaging findings. AJNR Am J Neuroradiol 2005;26:96-9. [3] Giannas JE, Bayat A, Davenport PJ. Heterotopic nasopharyngeal brain tissue associated with cleft palate. Br J Plast Surg 2005;58: 862-4.
www.elsevier.com/locate/jpedsurg
Parapharyngeal neuroglial heterotopia extending through the skull base in a neonate with airway obstruction Thierry A.G.M. Huisman a,⁎, Ulrike Brehmer a , Georg Zeilinger b , Thomas Stallmach c , Claudine Gysin d a
Department of Diagnostic Imaging, University Hospital Zurich, CH-8032 Zurich, Switzerland Department of Neonatology, Kantonsspital Aarau, CH-5001 Aarau, Switzerland c Department of Pathology, University Hospital Zurich, CH-8032 Zurich, Switzerland d Department of Surgery, University Children's Hospital Zurich, CH-8032 Zurich, Switzerland b
Index words: Heterotopic brain tissue; Parapharyngeal; MRI
Abstract We present a neonate with heterotopic nasopharyngeal brain tissue causing airway obstruction. Preoperative imaging showed extension of the mass along major neurovascular pathways into the cranial vault. Preoperative identification of intracranial extension is essential for planning surgery to prevent postoperative cerebrospinal fluid leaks or possible meningitis. © 2007 Elsevier Inc. All rights reserved.
Parapharyngeal masses in the neonate are rare and may cause airway obstruction. The differential diagnosis includes a variety of lesions such as cystic hygroma, hemangioma, glioma, encephalocele, meningocele, teratoma, branchial cleft anomaly, neurofibroma, and sarcoma [1,2]. Heterotopic parapharyngeal neuroglial tissue or heterotopic parapharyngeal brain tissue is a rare finding [1,2]. These lesions are composed of differentiated neuroectodermal derivates such as neurons, astrocytes, ependymal cells, and choroid plexus. They may be cystic because of the production of a fluid that resembles cerebrospinal fluid (CSF). By definition, there should be no continuity or communication with the cranial vault and its contents [3]. We report on a term neonate who presented with airway obstruction owing to parapharyngeal neuroglial heterotopia
⁎ Corresponding author. Tel.: +41 44 266 7110; fax: +41 44 266 7161. E-mail address: [email protected] (T.A.G.M. Huisman). 0022-3468/$ – see front matter © 2007 Elsevier Inc. All rights reserved. doi:10.1016/j.jpedsurg.2007.06.014
that extended through the skull base into the cavernous sinus and Meckel cave.
1. Case report We report on a term neonate who presented with an obstructed nasal respiration and a significant inspiratory and expiratory stridor. Symptoms aggravated in the supine position. On day 5 of life, endoscopy revealed a large epipharyngeal mass protruding into the oropharynx with infiltration of the soft palate. In addition, a mild laryngomalacia was noted. Tumor biopsy was performed. Histologic findings were nonconclusive. Magnetic resonance imaging (MRI) showed a large, T1 and T2 heterogeneous, partially cystic, partially solid tumor within the right parapharyngeal space (Fig. 1A and B). The tumor extended into the masticator space, the pterygopalatine fossa, and along the internal carotid artery into the cavernous sinus. In addition,
Parapharyngeal neuroglial heterotopia
1765
Fig. 1 A, Coronal T2-weighted fast spin-echo (FSE) magnetic resonance images. The heterotopic brain tissue presents as an inhomogeneous, partially hyperintense, partially hypointense lesion within the right parapharyngeal space (left image, arrows). Hypointense, solid components extend along the carotid artery and the maxillary nerve into the right cavernous sinus (middle and right images, arrows). B, Axial T2-weighted FSE magnetic resonance images. The left parapharyngeal component is moderately hyperintense (arrows) and displaces the right parotid gland laterally and the pterygoid muscles anteriorly. The mass also extends into the right cavernous sinus and inferior orbital fissure (arrowheads). The parapharyngeal component is partially isointense to the brain parenchyma.
the tumor reached Meckel cave through the foramen rotundum (Fig. 1A and B). The skull base was unremarkable; no bony defects were seen. The brain was without abnormality. Subsequently, a subtotal tumor resection was achieved using a lateral approach. Histologic analysis of the tumor showed mature neuroglial tissue, ependymal cells, and choroid plexus elements. The neuroglial tissue showed a positive immunohistochemical expression of glial fibrillary acid protein. No meningeal structures were identified. The tumor location in combination with the histologic and MRI findings led to the diagnosis of a parapharyngeal neuroglial heterotopia. The girl recovered well from surgery. Persisting swallowing problems required placement of a percutaneous gastric tube. The child developed well 1 year after surgery. Follow-up MRI showed stable residual tumor tissue within the parapharyngeal space (Fig. 2A and B).
2. Discussion Heterotopic neuroglial tissue or heterotopic brain is a rare anomaly composed of differentiated derivates of the
neuroectoderm outside the cranial vault or spinal canal and without communication with the brain, spinal cord, or meninges [1-3]. Brain heterotopia is most frequently seen in the nasal cavity. Rarely, heterotopia has been reported in the scalp, orbit, pterygopalatine fossa, pharynx, palate, lips, tongue, middle ear, and neck [1-3]. Patients usually present in the neonatal period with airway obstruction, swallowing difficulties, or a focal neck swelling. Heterotopic neuroglial tissue within the pharynx should be differentiated from skull base meningoencephaloceles and nasal gliomas. The surgical approach and technique as well as the possible complications differ, however, significantly. Preoperative imaging should characterize and localize the lesion. In particular, an intracranial extension should be excluded. Meningoencephaloceles will show a direct communication through a skull base defect with the cranial vault. Nasal gliomas contain glial cells; they lack, however, more complex elements such as neurons, ependymal-lined structures, or functioning choroid plexus tissue [1]. Consequently, they will have a more homogeneous appearance and signal intensity on MRI. The pathogenesis of heterotopic brain tissue is not yet fully understood. Several theories have been proposed
1766
T.A.G.M. Huisman et al.
Fig. 2 A, Postoperative follow-up axial T2-weighted FSE magnetic resonance images. A residual component is seen within the right parapharyngeal and infratemporal space (arrows). The anterior component is cystic in nature. Unchanged appearance of the solid components within the right cavernous sinus and inferior orbital fissure (arrowheads). B, Coronal T1-weighted magnetic resonance images. The cystic parapharyngeal component is T1 hypointense and CSF isointense (arrows). The solid component that extends into the cavernous sinus is T1 hypointense and isointense to the brain parenchyma (arrowhead). The right foramen rotundum lacks the hyperintense perineural fat tissue and is consequently hypointense compared with the left side (slim arrows).
including (a) encephaloceles that lost their cranial connection during development of the skull base, (b) displaced totipotent neuroectodermal cells that developed into mature neural tissue, and (c) entrapment of erroneously migrated olfactory bulb glial cells [1,3]. Currently the encephalocele theory is most widely accepted [3]. Imaging is essential to localize and characterize the lesion. Computed tomography and MRI are complementary imaging modalities. The high soft tissue resolution of MRI is especially helpful to localize and characterize the lesion. Computed tomography is advantageous because it may show osseous complications such as erosion of the adjacent skull base, mandible, or pterygoid plates. Reviewing the literature, we found that the key feature of heterotopic parapharyngeal brain heterotopia is the lack of an
extension into the cranial vault. Giannas et al [3] discussed, however, that there is a theoretical possibility of an intracranial communication of the heterotopic brain tissue. This could potentially lead to a CSF leak after surgery. Our case is of importance because this intracranial extension was identified by preoperative MRI. The lesion extended into the cavernous sinus along the internal carotid artery and reached the Meckel cave along the maxillary nerve. Magnetic resonance imaging had ruled out a meningoencephalocele. In addition, MRI had ruled out coexisting brain anomalies. In conclusion, our case demonstrates that heterotopic parapharyngeal brain tissue may extend into the cranial vault following neurovascular pathways. Consequently, preoperative imaging is mandatory to plan surgery in order to prevent CSF leaks.
Parapharyngeal neuroglial heterotopia
References [1] Behar PM, Muller S, Gerber ME, et al. Heterotopic neuroglial tissue causing airway obstruction in the newborn. Arch Otolaryngol Head Neck Surg 2001;127:997-1002.
1767 [2] Chen CY, Huang JH, Choi WM, et al. Parapharyngeal neuroglial heterotopia presenting as a growing single locular cyst: MR imaging findings. AJNR Am J Neuroradiol 2005;26:96-9. [3] Giannas JE, Bayat A, Davenport PJ. Heterotopic nasopharyngeal brain tissue associated with cleft palate. Br J Plast Surg 2005;58: 862-4.