The Journal of Laryngology and Otology July 1992, Vol. 106, pp. 643-648
Plexiform neurofibroma of the cervical portion of the vagus nerve J. GALLI, G. ALMADORI, G. PALUDETTI, M. ROSIGNOLI, L. CORINA, A. IERACI* (Rome, Italy)
Abstract The authors describe a rare case of plexiform neurofibroma of the cervical portion of the vagus nerve, and discuss its aetiopathogenesis, clinical, histological and therapeutic features, emphasizing the difference from other benign tumours of the vagus nerve. The clinical characteristics of the mass, ultrasound tomography, CT scanning and digital subtraction angiography were useful in defining its extension and relationships with the surrounding structures. Surgery is the treatment of choice. After mentioning the most commonly employed surgical approaches, they emphasize the advantages of the lateral-cervical approach which allows a wide exposure of the possible sites of origin of the tumour and its complete removal. Finally they stress the need of an accurate histological and immunohistochemical examination in order to differentiate neurofibromas from neurilemmomas.
Introduction In this paper a rare case of neurofibroma of the cervical portion of the vagus nerve is presented. It differs histologically from others benign tumours of the vagus nerve such as paragangliomas and neurilemmomas, but their clinical behaviour is almost alike (Harkin, 1986).
years) left lateral cervical mass whose size had increased during the last two years without producing any clinical symptoms (Fig. la). The medical history was negative, and there was no family history of benign neural tumours. An irregular, multilobulated mass extending from the jugulodigastric region to the supraclavicular fossa, deep to the left sternocleidomastoid muscle was detected. The left lateral wall of the naso, oro and hypopharynx and the ipsilateral tonsil were pushed medially (Fig. lb).
Case report A 19-year-old male, presented with a long lasting (about nine
FIG.
la
FIG. FIG.
lb
1
An external view of the long lasting left lateral-cervical and retromandibular mass (a). Endoral picture shows a pronounced bulge in the oropharyngeal wall (b).
From the Institute of Otorhinolaryngology and *Institute of Pathology of the Catholic University of the Sacred Heart, Rome, Italy. Accepted for publication: 26 March 1992 643
644
J. GALLI, G. ALMADORI, G. PALUDETTI, M. ROSIGNOLI. L. CORINA, A. IERACI
The patient underwent routine tests, ultrasound tomography and a CT scan followed by angiography of the left carotid artery. Ultrasound tomography showed a solid heterogeneous ovoid mass 5 cm in diameter and other smaller lymph node-like masses. The CT scan showed the presence of a solid, non-homogeneous hyperdense mass, extending from the base of the neck to the condylar region, displacing the deep vascular axis and the upper aerodigestive tract (Figs. 2&3). Digital subtraction angiography of the left internal and external carotid arteries showed a poorly vascularized mass pressing, stretching and displacing backwards the internal carotid and internal maxillary arteries. The mass was removed through left cervical approach, Fig. 4 (a,b). It appeared bulky, multilobulated, 25 cm long, and radi-
FIG.
Pre-operative CT axial scans. The images show a non-homogeneous hyperdense mass extending from the supraclavicular region (a) to the hyoid (b) and submandibular (c) regions, pressing and displacing the deep vascular axis of the neck, trachea and larynx.
3a
Pre-operative CT coronal scans. The mass extends from the low lateral cervical region to the trans-condyloyd line (a) displacing and pressing the upper aerodigestive tract (b).
645
CLINICAL RECORDS
FIG.
FIG.
4a
ating many branches from a main longitudinal body (Fig. 5); a shiny grey in colour and of parenchymatous consistency. The mass extended from the jugular foramen, down to the spinal and supraclavicular fossa, displacing the carotid artery. In order to remove the parapharyngeal masses it became necessary to sacrifice the lingual and facial arteries and the Xllth cranial nerve. Histology showed a neurofibroma. Some days after surgery, a repeat CT scan of the skull and the neck was performed: no cerebral masses could be detected and hyperdense scar tissue replacing the tumour could be observed. The vascular axis and the upper aerodigestive tract had returned to their position. The patient was discharged after 17 days with a deficit of the IXth, Xth, Xlth and Xllth left cranial nerves. Discussion Neurogenic tumours of the neck can originate from the IXth, Xth, Xlth and Xllth pair of cranial nerves, the superior and middle cervical ganglia, the sympathetic chain, the cervical and brachial plexus (Decurtins et al., 1988). As far as the vagus nerve is concerned 135 paragangliomas, 90
FIG. 5 Macroscopic view of the surgical specimen. Its length was 25 cm.
4b
FIG. 4 Intraoperative specimen. The lateral-cervical approach allows a wide surgical exposure of the mass (a) that appears plexiform and multilobulated (b).
neurilemmomas, and nine neurofibromas have been described in the literature. Paragangliomas originate from the glomus tissue of the nodosa ganglion (Gill et al., 1988), neurilemmomas mainly from the portion of the nerve adjacent to the nodosa ganglion (St Pierre et al., 1985), whereas neurofibromas at different levels along the course of the nerve such as the j ugular foramen, within the parapharyngeal space, in the low cervical region, near to the larynx, the trachea and within the tracheoesophageal space (Peetermans et al., 1991). A neurofibroma of the cervical portion of the vagus nerve is a rare tumour; it occurs in both males and females, more frequently in the right side and in subjects aged between 10 and 80 years with two peaks around 30 and 55 years (Krueger et al., 1979; Gacek et al., 1983). Clinically the tumour appears as a persistent high lateral cervical mass and, endorally, as a bulge to the tonsillar region, seldom associated with dysphagia, aspiration, ipsilateral vocal fold palsy, cervico-facial pain, 'lump in the throat sensation' and hoarseness (Bocca et al., 1984). An accurate clinical history is important in order to exclude previous radiotherapy of the cervical regions and a family history of von Recklinghausen's disease (White et al., 1986). The visual and digital inspection of both the pharynx and the lateral cervical region, allow us to define the consistency, mobility, surface characteristics of the mass, the absence of pain, the congestion and the local temperature (Green et al., 1988). The extension, the relationships with the adjacent structures and, in some cases, also the presumptive nature of tumours can be defined by means of ultrasound tomography or imaging techniques such as MRI, CT scan, sialography (Peetermans et al., 1991). On CT, a neurofibroma appears as a non-homogeneous hyper dense mass (Silver et al., 1984) neoplasm. If, on the contrary, the mass is uniformly enhanced by the contrast material, digital substraction or formal angiography has to be performed in order to allow a differential diagnosis from vascular tumours such as paragangliomas. If the tumour has marked vascularity, the level of urinary catecholamines must be estimated (Gill et al., 1988; Thomassin et al., 1989). Finally if on CT scanning, the mass appears isodense or hypo-
646
J. GALLI, G. ALMADORI, G. PALUDETTI, M. ROSIGNOLI, L. CORINA, A. IERACI
FIG. 6 Typical appearance of a neurofibroma: Schwann cells are associated with wire-like collagen fibrils from which they are separated by a moderate amount of mucosubstances.
A )!
\
J' FIG. 7 Showing the positivity for S-100 protein of the Schwann cells.
647
CLINICAL RECORDS
, .%'t i . •'.
* .•-
FIG. 8 B.S., 19 years. Positive immunoreactivity for Vimentin of the collagen fibres.
dence, we are probably dealing with a salivary gland tumour or with a cervical lipoma (Silver and Mawad, 1984). Sialography, sialoCT or possibly an ultrasound tomography have to be performed when a tumour, involving the deep lobe of the parotid gland, is suspected (Som et al., 1984). Recently, MRI with GdDPTA has been recommended to help differentiate the various type of tumours as it clearly defines its size, location and relationship with the deep vascular axis of the neck (Som and Braun, 1987). Surgery is the treatment of choice. We agree with Green et al. (1988) and Peetermans et al. (1991) in using a lateral-cervical approach allowing wide exposure of the possible sites of origin of the neurofibroma, its dissection from the vagus nerve and its complete removal. In the case described, the tumour was plexiform and multilobated, and only a wide exposure could define its real extent. When the tumour spreads through the jugular foramen, a combined intra- and extra-cranial approach, e.g. the transtemporal, becomes necessary (Franklin et al., 1989). If tumours are located in the parapharyngeal space, the mandibular swing procedure can be used which allows a wide exposure of the carotid artery and of the parapharyngeal space (Som etal., 1981; Green et al., 1988). After surgery, a temporary or permanent deficit of the IXth, Xth, Xlth, Xllth cranial nerves may become evident. An accurate histological examination is crucial in order to differentiate neurofibromas from neurilemmomas: the latter derive from the Schwann cells while the former from the perineural cells producing connective tissue (Chang and Schi, 1984; Harkin etal., 1986). Neurofibromas are characterized by interlacing bundles of elongated cells containing wavy, dark-staining nuclei (Schwann
cells). The cells are intimately associated with wire-like strands of collagen from which they are separated by a small to moderate amount of mucoid material (Fig. 6). Small neurites can usually be demonstrate throughout these tumours (Erlandson and Wardruff, 1982). Neurilemmomas, instead, arise from the endoneural Schwann cells and contain little connective tissue (Cheong et al., 1991). However several intermediate forms between neurofibromas and neurilemmomas exist: in these cases immunohistochemistry should be performed using polyclonal antibodies against Glial Fibrillary Acidic Protein (GFAP), S-100 protein, Neuron specific Enolase (NSE), and monoclonal antibodies against Neurofilaments (6B9), Epithelial Membrane Antigen (EMA) and Common Leukocyte Antigen (CLA) (Peetermans et al., 1991). We utilized the immunohistochemical stains for S-100, GFAP, NSE and Vimentin that emphasized a sharp positivity of S-100 protein towards the Schwann cells still present in the tumour, and of Vimentin towards collagen fibrils (Figs. 7 & 8). These histological and immunohistochemical findings allowed us to clearly define the mass as a neurofibroma. References Bocca, E. (1984) Tumori parafaringei. In: Tumefazioni cervicali. Relazione Ufficiale 71 Congresso Societa' Italiana di Otorinolaringologia e Chirurgia Cervico-Facciale, Pacini, Pisa: 299-318. Chang, S. C, Schi, Y. M. (1984) Neurilemmoma of the vagus nerve. A case report and brief literature review. Laryngoscope, 94: 946^9. Cheong, S. P., Kwang, W. S., Choon, K. K. (1991) Neurilemmomas of the cervical vagus nerve. Archives of Otolaryngology—Head and Neck Surgery , 13: 439^41. Decurtins, C, Wey, W., Moll, C. (1988) Schwannoma and neurofibroma of the neck. HNO, 36: 437^44.
648
J. GALLI, G. ALMADORI, G. PALUDETTI, M. ROSIGNOLI, L. CORINA, A. IERACI
Erlandson, R. A., Woodruff, J. M. (1982) Peripheral nerve sheath tumours. Cancer, 49: 273—287. Franklin, D. J., Moore, G. R, Fish, U. (1989) Jugular foramen peripheral nerve sheath tumours. Laryngoscope, 99: 1081-1087. Gacek, R. R. (1983) Pathology of jugular foramen neurofibroma. Annals of Otology, Rhinology and Laryngology, 92: 128—133. Gill, P. S., Valentine, R. G., Oiler, D. W., Rob, C. G. (1988) Intravagal paraganglioma: report of a case and a discussion of vascular parapharyngeal masses. Surgery, 103: 432-^-37. Green, J. D., Olsen, K. D. (1988) Neoplasm of the vagus nerve. Laryngoscope, 98: 648-654. Harkin, J. C. (1986) Pathology of nerve sheath tumours. Annals of the New York Academy of Sciences, 486: 147-154. Krueger, W., Weisberger, E., Ballantyne, A. J., Goepfert, H. (1979) Plexiform neurofibroma of the head and neck. American Journal of Surgery, 138: 517-520. Peetermans, J. F., Van de Heyning, P. H., Parizel, P. N., Martin, J. J., Forton, G. E., Vanmaele, R. G., Valcke, H. H., Marquet, J. E, De Schepper, A. M. (1991) Neurofibroma of the vagus nerve in the head and neck: a case report. Archives of Otolaryngology—Head and Neck Surgery, 13: 56-61. Silver, J. A., Mawad, M. E. (1984) Computed tomography of the carotid space and related cervical spaces. Part II: neurogenic tumours. Radiology, 150: 729-735. Som, P. M., Biller, H. F. (1981) Tumours of the parapharyngeal space. Preoperative evaluation, diagnosis and surgical
Key words: Neurofibroma; vagus nerve
approaches. Annals of Otology, Rhinology and Laryngology, Supplement 80: 3-15. Som, P. M., Biller, H. E, Lawson, W., Sacher, M., Lanzieri, C. F. (1984) Parapharyngeal space masses: an updated protocol based upon 104 cases. Radiology, 153: 149-156. Som, P. M., Braun, I. E, Shapiro, M. D., Reede, D. L., Curtin, H. D., Zimmerman, R. A. (1987) Tumours of the parapharyngeal space and upper neck: MR imaging characteristics. Radiology, 164: 823-829. St. Pierre, S., Theriault, R., Le Clerc, J. E. (1985) Schwannomas of the vagus nerve in head and neck. Journal of Otolaryngology, 14: 167-170. Thomassin, J. M., Zanaret, M., Inedjian, J. M., Canale, H., Cannoni, M., Pech, A. (1989) Laterocervical paraganglioma. Revue de Laryngologie, Otologie, Rhinologie, 110: 213-217. White, A. K., Smith, R. J. H., Bigler, C. R., Brooke, W. E, Shauer, P. R. (1986) Head and neck manifestations of neurofibromatosis. Laryngoscope, 96: 732-737. Address for correspondence: Jacopo Galli, M. D., Institute of Otorhinolaryngology of the Catholic University of the Sacred Heart, Largo Agostino Gemelli, 8, 00168 Roma (Italy)
Plexiform neurofibroma of the cervical portion of the vagus nerve J. GALLI, G. ALMADORI, G. PALUDETTI, M. ROSIGNOLI, L. CORINA, A. IERACI* (Rome, Italy)
Abstract The authors describe a rare case of plexiform neurofibroma of the cervical portion of the vagus nerve, and discuss its aetiopathogenesis, clinical, histological and therapeutic features, emphasizing the difference from other benign tumours of the vagus nerve. The clinical characteristics of the mass, ultrasound tomography, CT scanning and digital subtraction angiography were useful in defining its extension and relationships with the surrounding structures. Surgery is the treatment of choice. After mentioning the most commonly employed surgical approaches, they emphasize the advantages of the lateral-cervical approach which allows a wide exposure of the possible sites of origin of the tumour and its complete removal. Finally they stress the need of an accurate histological and immunohistochemical examination in order to differentiate neurofibromas from neurilemmomas.
Introduction In this paper a rare case of neurofibroma of the cervical portion of the vagus nerve is presented. It differs histologically from others benign tumours of the vagus nerve such as paragangliomas and neurilemmomas, but their clinical behaviour is almost alike (Harkin, 1986).
years) left lateral cervical mass whose size had increased during the last two years without producing any clinical symptoms (Fig. la). The medical history was negative, and there was no family history of benign neural tumours. An irregular, multilobulated mass extending from the jugulodigastric region to the supraclavicular fossa, deep to the left sternocleidomastoid muscle was detected. The left lateral wall of the naso, oro and hypopharynx and the ipsilateral tonsil were pushed medially (Fig. lb).
Case report A 19-year-old male, presented with a long lasting (about nine
FIG.
la
FIG. FIG.
lb
1
An external view of the long lasting left lateral-cervical and retromandibular mass (a). Endoral picture shows a pronounced bulge in the oropharyngeal wall (b).
From the Institute of Otorhinolaryngology and *Institute of Pathology of the Catholic University of the Sacred Heart, Rome, Italy. Accepted for publication: 26 March 1992 643
644
J. GALLI, G. ALMADORI, G. PALUDETTI, M. ROSIGNOLI. L. CORINA, A. IERACI
The patient underwent routine tests, ultrasound tomography and a CT scan followed by angiography of the left carotid artery. Ultrasound tomography showed a solid heterogeneous ovoid mass 5 cm in diameter and other smaller lymph node-like masses. The CT scan showed the presence of a solid, non-homogeneous hyperdense mass, extending from the base of the neck to the condylar region, displacing the deep vascular axis and the upper aerodigestive tract (Figs. 2&3). Digital subtraction angiography of the left internal and external carotid arteries showed a poorly vascularized mass pressing, stretching and displacing backwards the internal carotid and internal maxillary arteries. The mass was removed through left cervical approach, Fig. 4 (a,b). It appeared bulky, multilobulated, 25 cm long, and radi-
FIG.
Pre-operative CT axial scans. The images show a non-homogeneous hyperdense mass extending from the supraclavicular region (a) to the hyoid (b) and submandibular (c) regions, pressing and displacing the deep vascular axis of the neck, trachea and larynx.
3a
Pre-operative CT coronal scans. The mass extends from the low lateral cervical region to the trans-condyloyd line (a) displacing and pressing the upper aerodigestive tract (b).
645
CLINICAL RECORDS
FIG.
FIG.
4a
ating many branches from a main longitudinal body (Fig. 5); a shiny grey in colour and of parenchymatous consistency. The mass extended from the jugular foramen, down to the spinal and supraclavicular fossa, displacing the carotid artery. In order to remove the parapharyngeal masses it became necessary to sacrifice the lingual and facial arteries and the Xllth cranial nerve. Histology showed a neurofibroma. Some days after surgery, a repeat CT scan of the skull and the neck was performed: no cerebral masses could be detected and hyperdense scar tissue replacing the tumour could be observed. The vascular axis and the upper aerodigestive tract had returned to their position. The patient was discharged after 17 days with a deficit of the IXth, Xth, Xlth and Xllth left cranial nerves. Discussion Neurogenic tumours of the neck can originate from the IXth, Xth, Xlth and Xllth pair of cranial nerves, the superior and middle cervical ganglia, the sympathetic chain, the cervical and brachial plexus (Decurtins et al., 1988). As far as the vagus nerve is concerned 135 paragangliomas, 90
FIG. 5 Macroscopic view of the surgical specimen. Its length was 25 cm.
4b
FIG. 4 Intraoperative specimen. The lateral-cervical approach allows a wide surgical exposure of the mass (a) that appears plexiform and multilobulated (b).
neurilemmomas, and nine neurofibromas have been described in the literature. Paragangliomas originate from the glomus tissue of the nodosa ganglion (Gill et al., 1988), neurilemmomas mainly from the portion of the nerve adjacent to the nodosa ganglion (St Pierre et al., 1985), whereas neurofibromas at different levels along the course of the nerve such as the j ugular foramen, within the parapharyngeal space, in the low cervical region, near to the larynx, the trachea and within the tracheoesophageal space (Peetermans et al., 1991). A neurofibroma of the cervical portion of the vagus nerve is a rare tumour; it occurs in both males and females, more frequently in the right side and in subjects aged between 10 and 80 years with two peaks around 30 and 55 years (Krueger et al., 1979; Gacek et al., 1983). Clinically the tumour appears as a persistent high lateral cervical mass and, endorally, as a bulge to the tonsillar region, seldom associated with dysphagia, aspiration, ipsilateral vocal fold palsy, cervico-facial pain, 'lump in the throat sensation' and hoarseness (Bocca et al., 1984). An accurate clinical history is important in order to exclude previous radiotherapy of the cervical regions and a family history of von Recklinghausen's disease (White et al., 1986). The visual and digital inspection of both the pharynx and the lateral cervical region, allow us to define the consistency, mobility, surface characteristics of the mass, the absence of pain, the congestion and the local temperature (Green et al., 1988). The extension, the relationships with the adjacent structures and, in some cases, also the presumptive nature of tumours can be defined by means of ultrasound tomography or imaging techniques such as MRI, CT scan, sialography (Peetermans et al., 1991). On CT, a neurofibroma appears as a non-homogeneous hyper dense mass (Silver et al., 1984) neoplasm. If, on the contrary, the mass is uniformly enhanced by the contrast material, digital substraction or formal angiography has to be performed in order to allow a differential diagnosis from vascular tumours such as paragangliomas. If the tumour has marked vascularity, the level of urinary catecholamines must be estimated (Gill et al., 1988; Thomassin et al., 1989). Finally if on CT scanning, the mass appears isodense or hypo-
646
J. GALLI, G. ALMADORI, G. PALUDETTI, M. ROSIGNOLI, L. CORINA, A. IERACI
FIG. 6 Typical appearance of a neurofibroma: Schwann cells are associated with wire-like collagen fibrils from which they are separated by a moderate amount of mucosubstances.
A )!
\
J' FIG. 7 Showing the positivity for S-100 protein of the Schwann cells.
647
CLINICAL RECORDS
, .%'t i . •'.
* .•-
FIG. 8 B.S., 19 years. Positive immunoreactivity for Vimentin of the collagen fibres.
dence, we are probably dealing with a salivary gland tumour or with a cervical lipoma (Silver and Mawad, 1984). Sialography, sialoCT or possibly an ultrasound tomography have to be performed when a tumour, involving the deep lobe of the parotid gland, is suspected (Som et al., 1984). Recently, MRI with GdDPTA has been recommended to help differentiate the various type of tumours as it clearly defines its size, location and relationship with the deep vascular axis of the neck (Som and Braun, 1987). Surgery is the treatment of choice. We agree with Green et al. (1988) and Peetermans et al. (1991) in using a lateral-cervical approach allowing wide exposure of the possible sites of origin of the neurofibroma, its dissection from the vagus nerve and its complete removal. In the case described, the tumour was plexiform and multilobated, and only a wide exposure could define its real extent. When the tumour spreads through the jugular foramen, a combined intra- and extra-cranial approach, e.g. the transtemporal, becomes necessary (Franklin et al., 1989). If tumours are located in the parapharyngeal space, the mandibular swing procedure can be used which allows a wide exposure of the carotid artery and of the parapharyngeal space (Som etal., 1981; Green et al., 1988). After surgery, a temporary or permanent deficit of the IXth, Xth, Xlth, Xllth cranial nerves may become evident. An accurate histological examination is crucial in order to differentiate neurofibromas from neurilemmomas: the latter derive from the Schwann cells while the former from the perineural cells producing connective tissue (Chang and Schi, 1984; Harkin etal., 1986). Neurofibromas are characterized by interlacing bundles of elongated cells containing wavy, dark-staining nuclei (Schwann
cells). The cells are intimately associated with wire-like strands of collagen from which they are separated by a small to moderate amount of mucoid material (Fig. 6). Small neurites can usually be demonstrate throughout these tumours (Erlandson and Wardruff, 1982). Neurilemmomas, instead, arise from the endoneural Schwann cells and contain little connective tissue (Cheong et al., 1991). However several intermediate forms between neurofibromas and neurilemmomas exist: in these cases immunohistochemistry should be performed using polyclonal antibodies against Glial Fibrillary Acidic Protein (GFAP), S-100 protein, Neuron specific Enolase (NSE), and monoclonal antibodies against Neurofilaments (6B9), Epithelial Membrane Antigen (EMA) and Common Leukocyte Antigen (CLA) (Peetermans et al., 1991). We utilized the immunohistochemical stains for S-100, GFAP, NSE and Vimentin that emphasized a sharp positivity of S-100 protein towards the Schwann cells still present in the tumour, and of Vimentin towards collagen fibrils (Figs. 7 & 8). These histological and immunohistochemical findings allowed us to clearly define the mass as a neurofibroma. References Bocca, E. (1984) Tumori parafaringei. In: Tumefazioni cervicali. Relazione Ufficiale 71 Congresso Societa' Italiana di Otorinolaringologia e Chirurgia Cervico-Facciale, Pacini, Pisa: 299-318. Chang, S. C, Schi, Y. M. (1984) Neurilemmoma of the vagus nerve. A case report and brief literature review. Laryngoscope, 94: 946^9. Cheong, S. P., Kwang, W. S., Choon, K. K. (1991) Neurilemmomas of the cervical vagus nerve. Archives of Otolaryngology—Head and Neck Surgery , 13: 439^41. Decurtins, C, Wey, W., Moll, C. (1988) Schwannoma and neurofibroma of the neck. HNO, 36: 437^44.
648
J. GALLI, G. ALMADORI, G. PALUDETTI, M. ROSIGNOLI, L. CORINA, A. IERACI
Erlandson, R. A., Woodruff, J. M. (1982) Peripheral nerve sheath tumours. Cancer, 49: 273—287. Franklin, D. J., Moore, G. R, Fish, U. (1989) Jugular foramen peripheral nerve sheath tumours. Laryngoscope, 99: 1081-1087. Gacek, R. R. (1983) Pathology of jugular foramen neurofibroma. Annals of Otology, Rhinology and Laryngology, 92: 128—133. Gill, P. S., Valentine, R. G., Oiler, D. W., Rob, C. G. (1988) Intravagal paraganglioma: report of a case and a discussion of vascular parapharyngeal masses. Surgery, 103: 432-^-37. Green, J. D., Olsen, K. D. (1988) Neoplasm of the vagus nerve. Laryngoscope, 98: 648-654. Harkin, J. C. (1986) Pathology of nerve sheath tumours. Annals of the New York Academy of Sciences, 486: 147-154. Krueger, W., Weisberger, E., Ballantyne, A. J., Goepfert, H. (1979) Plexiform neurofibroma of the head and neck. American Journal of Surgery, 138: 517-520. Peetermans, J. F., Van de Heyning, P. H., Parizel, P. N., Martin, J. J., Forton, G. E., Vanmaele, R. G., Valcke, H. H., Marquet, J. E, De Schepper, A. M. (1991) Neurofibroma of the vagus nerve in the head and neck: a case report. Archives of Otolaryngology—Head and Neck Surgery, 13: 56-61. Silver, J. A., Mawad, M. E. (1984) Computed tomography of the carotid space and related cervical spaces. Part II: neurogenic tumours. Radiology, 150: 729-735. Som, P. M., Biller, H. F. (1981) Tumours of the parapharyngeal space. Preoperative evaluation, diagnosis and surgical
Key words: Neurofibroma; vagus nerve
approaches. Annals of Otology, Rhinology and Laryngology, Supplement 80: 3-15. Som, P. M., Biller, H. E, Lawson, W., Sacher, M., Lanzieri, C. F. (1984) Parapharyngeal space masses: an updated protocol based upon 104 cases. Radiology, 153: 149-156. Som, P. M., Braun, I. E, Shapiro, M. D., Reede, D. L., Curtin, H. D., Zimmerman, R. A. (1987) Tumours of the parapharyngeal space and upper neck: MR imaging characteristics. Radiology, 164: 823-829. St. Pierre, S., Theriault, R., Le Clerc, J. E. (1985) Schwannomas of the vagus nerve in head and neck. Journal of Otolaryngology, 14: 167-170. Thomassin, J. M., Zanaret, M., Inedjian, J. M., Canale, H., Cannoni, M., Pech, A. (1989) Laterocervical paraganglioma. Revue de Laryngologie, Otologie, Rhinologie, 110: 213-217. White, A. K., Smith, R. J. H., Bigler, C. R., Brooke, W. E, Shauer, P. R. (1986) Head and neck manifestations of neurofibromatosis. Laryngoscope, 96: 732-737. Address for correspondence: Jacopo Galli, M. D., Institute of Otorhinolaryngology of the Catholic University of the Sacred Heart, Largo Agostino Gemelli, 8, 00168 Roma (Italy)
