Cervical Sympathetic Chain Schwannomas Masquerading as Carotid Body Tumors

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1 Cervical Sympathetic Chain Schwannomas Masquerading as Carotid Body Tumors Jean M. Panneton, MD, and Barry W. Rusnak, MD, Rochester, Minnesota, and Winnipeg, Canada Cervical sympathetic chain (CSC) schwannoma is a rare neurogenic tumor that can mimic a carotid body tumor (CBT). Two male patients aged 33 and 49 years old were referred for a cervical mass thought to be a CBT. Both patients were found to have an asymptomatic, pulsatile, nontender mass located at the level of the angle of the mandible. Both patients were neurologically asymptomatic and cranial nerves were normal. Both patients underwent neck exploration and resection of the mass involving the CSC. Postoperatively, a Horner s syndrome was present. Histopathology confirmed both tumors to be schwannomas of the CSC. At follow-up, both patients are asymptomatic with no recurrence. The main imaging criterion to differentiate a CBT from a CSC schwannoma is the lack of hypervascularity of the latter. Malignant transformation is extremely rare. Tumor excision gives excellent results with no local recurrence. Horner s syndrome is an expected postoperative complication. (Ann Vasc Surg 2000;14: ) DOI: /s Patients presenting with a cervical mass in close relationship to the carotid bifurcation are often referred to vascular surgeons for evaluation and treatment. Carotid body tumors (CBTs) or paragangliomas are the most common lesions localized at the carotid bifurcation level. Cervical sympathetic chain (CSC) schwannoma is a rare neurogenic tumor that can mimic, by its presentation, a CBT. Only 28 cases of CSC schwannoma have been previously described in the literature. Two new cases are reported here along with a review of the literature to emphasize CSC schwannoma presentation, characteristics, management, and outcome. From the Division of Vascular Surgery, Mayo Clinic and Mayo Foundation, Rochester, MN (J.M.P.) and the Department of Radiology, St. Boniface General Hospital, Winnipeg, Canada (B.W.R.). Presented at the Priestly Society during the 60th Annual Mayo Alumni Association Meeting, Acapulco, Mexico, May 1, Correspondence to: J.M. Panneton, MD, Mayo Clinic, 200 First Street Southwest, Rochester, MN 55905, USA. CASE REPORTS Case 1 A 33-year-old man presented with a 1-year history of an asymptomatic left-sided neck mass. This pulsatile, nontender mass was located at the level of the angle of the mandible. He denied any trauma or recent infection and did not have any symptoms of dysphagia, dyspnea, or hoarseness. On examination the mass was cm at the level of the angle of the mandible. All cranial nerves were normal. Laryngoscopic results were normal. Computed tomography (CT) of the neck showed an enhancing mass medial to the carotid bifurcation with compression of the jugular vein. Initial diagnosis as suggested by CT scan was a CBT. A left carotid angiogram revealed splaying of the internal and external carotid arteries but without the expected hypervascularity of CBT. At operation, the mass was located medial and posterior to the carotid bifurcation. The vagal and hypoglossal nerves were identified and uninvolved. The CSC was emerging at the superior and inferior aspect of the mass. The mass was well defined, encapsulated, and easily shelled out. Early postoperative reexploration was required for evacuation of a wound hematoma. Bleeding arose from the capsule of the tumor. Resection of the 519

2 520 Case reports Annals of Vascular Surgery Fig. 1. CT of the neck showing a right-sided nonenhancing mass behind the carotid bifurcation with splaying of the internal and external carotid arteries and partial compression of the jugular vein. Fig. 2. A Coronal view of a MRI showing a right-sided well-circumscribed, ovoid mass causing lateral displacement of the carotid vessels. B Transverse view of a gadolinium-enhanced MRI of the neck showing an enhancing mass at the level of the carotid bifurcation causing splaying of the internal and external carotid vessels. capsule with ligation and division of the CSC was required for hemostasis. Postoperatively, the patient had a left-sided Horner s syndrome. At histopathology, the mass was confirmed to be a schwannoma of the CSC. At 2 and 1/2 years follow-up the patient is asymptomatic with no recurrence. Case 2 A right-sided neck mass was discovered during a carotid duplex ultrasound in a 49-year-old man. The patient was asymptomatic. Examination revealed a nontender mass below the angle of the mandible. All cranial nerves were normal. Findings from oral examination and laryngoscopy were normal. A CT of the neck (Fig. 1) showed a2 2.5 cm nonenhancing mass at the level of the right carotid bifurcation. The carotid vessels and the jugular vein were displaced laterally. A magnetic resonance image (MRI) of the neck revealed a solid mass at the level of the carotid bifurcation with partial enhancement with gadolinium (Fig. 2). The MRI interpretation was carotid chemodectoma or CBT as opposed to the CT scan interpretation, which suggested a cervical schwannoma. A selective right carotid angiogram (Fig. 3) showed typical splaying of the internal and external carotid arteries, as would be expected for a CBT. However, the mass did lack the intense hypervascularity associated with CBT. At operation, the mass was located medial and posterior to the carotid bifurcation. The superior laryngeal nerve was found between the external carotid artery anteriorly and the mass posteriorly (Fig. 4). The tumor was encapsulated and the carotid vessels could be easily Fig. 3. Selective right carotid angiogram, again showing splaying of the carotid bifurcation with no hypervascularity in the mass. peeled away. At the cephalad and caudad end of the mass was the CSC. It was doubly ligated, proximally and distally, and the mass entirely resected. Postoperatively, the patient developed a right-sided Horner s syndrome. Histopathology (Fig. 5) confirmed the diagnosis of CSC schwannoma. At 10 months follow-up, there is no recurrence.

3 Vol. 14, No. 5, 2000 Case reports 521 Fig. 6. Transverse section of the parapharyngeal space at the carotid bifurcation level with closely related neurovascular structures. SCM, sternocleidomastoid muscle; Subm, submandibular gland. Table I. Differential diagnosis for lateral neck mass Fig. 4. Encapsulated tumor behind the splayed carotid bifurcation with intact hypoglossal, superior laryngeal, and vagal (not shown) nerves. Salivary gland tumors Neurogenic tumors Lymphatic Lymphoma Lymphangioma Metastatic lymphadenopathy Vascular Tumor Malformation Aneurysm Branchial cleft cyst Miscellaneous Table II. Classification of neurogenic tumors Fig. 5. Schwannoma ( 200); encapsulated tumor with spindle-shaped cells showing palisading pleiomorphic nuclei, with no mitosis. DISCUSSION Carotid body tumors and CSC schwannomas are both neurogenic tumors occupying the parapharyngeal space. The anatomic boundaries of the parapharyngeal space have been described previously in detail. 1-3 The styloid process divides the Nerve sheath cells Neurilemmoma or schwannoma Neurofibroma Solitary Von Recklinghausen s disease Paraganglion cells Paraganglioma or chemodectoma Carotid body tumor Glomus intravagale tumor Ganglion cells Ganglioneuroma Neuroblastoma Secondary tumor Meningioma parapharyngeal space into anterior and posterior compartments. The posterior parapharyngeal space contains the following important neurovascular structures: internal and external carotid arteries, in-

4 522 Case reports Annals of Vascular Surgery Table III. Review of cervical sympathetic chain schwannomas Reference Patient no. Age/sex Presentation Size (cm) Preop diagnosis Gibberd /M Painless mass 32/M Painless mass CSCS Mayo /F Painless mass 5 Amano 8 2 Callum /F Painless mass Lymph node Cullen and Monroe /F Painless mass 6 CBT 42/M Painless mass 5 CBT Brandt /F Rogers /F Painless mass Aberrant thyroid Kragh et al. 5 7 Daly and Roesler /M Painless mass 4.5 CSCS 66/M Painful mass 2.5 CBT or CSCS Brandenburg /F Painless mass 4 Branchial cyst Clifton /F Painless mass 4 Thyroid 45/F Painless mass 6 CBT Clairmont and Conley /F Painless mass 2 CBT Sharaki et al Myssiorek et al /F Painless mass 4.5 CBT or CSCS 59/M Painless mass CBT Takimoto et al /M Painless mass Partial Horner Panneton and Rusnak 2 33/M Painless mass 4 CBT (current study) 49/M Painless mass 2.5 CBT CBT, carotid body tumor; CSCS, cervical sympathetic chain schwannoma. Table IV. Clinical features of CSC schwannomas Mean age of 40.5 years Painless cervical mass Localized at carotid bifurcation Referral for suspected CBT Typical carotid bifurcation splaying Lack of hypervascularity Rare local recurrence ternal jugular vein, glossopharyngeal nerve (IX), vagus nerve (X), spinal accessory nerve (XI), hypoglossal nerve (XII), and CSC (Fig. 6). Postsynaptic fibers from the CSC branch off to the external carotid artery for facial sweating, whereas the fibers branching to the internal carotid artery are responsible for pupillary dilatation and eyelid elevation. Injury to the CSC will cause ipsilateral facial anhydrosis, ptosis, and myosis. This clinical triad is called Horner s syndrome. The differential diagnosis for patients presenting with a lateral neck mass is quite varied (Table I). Salivary gland tumors are the most common lesions. 3,4 Most parapharyngeal space tumors are benign. 3,4 The second-most common tumors of the parapharyngeal space are neurogenic. Both CBT or paragangliomas and schwannomas or neurilemmomas belong to that group (Table II). The two most common neurogenic tumors in the parapharyngeal space are the neurilemmoma and the paraganglioma. 3,4 Neurilemmomas or schwannomas may involve cranial nerves, cervical nerves, or the sympathetic chain. The two most commonly involved are the vagus nerve and the CSC. 5 It remains difficult to assess the relative incidence of CSC schwannoma and CBT. We reviewed all patients presenting with a parapharyngeal space neurogenic tumor during a 10-year period ( ) in our institution, which is one of two teaching tertiary care hospitals covering a population of roughly 1 million in the Canadian province of Manitoba. This review revealed only eight CBTs and three cervical schwannomas. Of these three, two are the CSC schwannomas reported here. The third case of schwannoma occupied the parapharyngeal space, but the nerve of origin could not be identified. A review of the literature revealed only 28 reported cases of CSC schwannoma (Table III). 1,5-18 This is in strong contrast to a recent report from Hallett and collaborators reporting a 50-year experience with 153 carotid body and cervical paragangliomas. 19 In a recent case report and review of the literature on

5 Vol. 14, No. 5, 2000 Case reports 523 Fig. 7. A Sagittal view of a MRI showing a well-defined ovoid mass at the carotid bifurcation level confirmed to be a CBT. B Transverse view of a gadolinium-enhanced MRI of the neck showing a CBT with significant enhancing. C MRA showing splaying of the internal and external carotid arteries by a CBT with typical hypervascularity. schwannoma of the cervical vagus nerve, a total of 74 cases was found. 20 The two patients reported here have clinical characteristics similar to those of other patients from the literature review found to have a CSC schwannoma (Table IV). Mean age was 40.5 years (range 5-66 years old). There was no gender difference (1 male:1.1 female). All patients but one presented with a painless mass on the lateral aspect of the neck behind the angle of the mandible. When stated, a preoperative diagnosis of CBT was suspected in most cases. All patients had resection of the CSC schwannoma. All patients developed a Horner s syndrome postoperatively and this complication was transient in only three patients. During follow-up, there were no cases of recurrence. Interestingly, only one patient (a 5-year-old boy) presented preoperatively with an incomplete Horner s syndrome. 18 Patients typically had lateral displacement of the carotid vessels as well as splaying of the carotid bifurcation and of the external and internal carotid arteries suggesting a CBT. Preoperative investigation with CT of the neck showed in most cases a partially or nonenhancing mass causing lateral displacement of the carotid vessels. A selective carotid angiogram also showed, in most cases, typical splaying of the carotid bifurcation suggesting a CBT (Fig. 3). However, the main imaging criterion to differentiate a CBT from a CSC schwannoma is the lack of hypervascularity of the latter. This difference is well demonstrated in Figure 7, which shows intense vascularity of a CBT by magnetic resonance angiogram (MRA). Magnetic resonance imaging can clearly delineate the location of a cervical mass in relationship with surrounding structures such as the carotid vessels and this can be done in transverse, sagittal, or coronal views (Figs. 2A, 2B, 7A, and 7B). Use of gadolinium allows the MRI study to show whether there is enhancement in the mass (Figs. 2B and 7B). An MRA will show typical splaying of the carotid vessels by either tumor. The MRA helped us to differentiate between these two tumors by showing the hypervascularity of the CBT (Fig. 7C) and the lack of hypervascularity in the CSC schwannoma. Typically, the gross appearance of a CSC schwannoma is a well-defined encapsulated tumor that averages 4.2 cm in diameter (range 2 to 6 cm). The mass also displays a large number of vessels at the level of the capsule. The tumor can be easily peeled away from the carotid or jugular vessels or adjacent nerves. This characteristic is actually what differentiates CSC schwannoma excision from CBT excision. The lack of intense vascularity of the CSC schwannoma makes excision relatively easier and the external carotid artery does not need to be sacrificed and resected as is often required with CBT excision. CSC schwannomas are benign, slow-growing tumors. Malignant transformation is extremely rare. During a 47-year study at the Mayo Clinic, there were 148 benign neurilemmomas of the head and neck compared to only 4 malignant neurilemmomas. 5

6 524 Case reports Annals of Vascular Surgery Surgical resection is recommended for CSC schwannomas. Excision of the tumor gives excellent results with no local recurrence. CSC schwannoma resection is well tolerated, with a transient or permanent Horner s syndrome being an expected complication. Careful, meticulous surgical technique is essential to avoid other neurovascular injuries as CSC tumors are localized in dissection zones II and III as described by Hallett and collaborators. 19 In all cases of CSC schwannoma resection reported, there were no cranial nerve injuries nor any perioperative strokes. CONCLUSION CSC schwannoma is a rare neurogenic tumor that can mimic a CBT. The clinical presentation is similar to that of the CBT, and the main differentiating criterion is the lack of intense vascularity typical of CBT. Magnetic resonance imaging is the diagnostic modality of choice. Surgical resection of CSC schwannoma is recommended. The risk of local recurrence is very low. Horner s syndrome is an expected postoperative complication. The authors gratefully acknowledge the assistance of Ms. Rhonda Hartman for manuscript preparation and Mr. David Factor for medical illustration. REFERENCES 1. Brandenburg JH. Symposium on malignancy. IV. Neurogenic tumors of the parapharyngeal space. Laryngoscope 1972;82: Bass RM. Approaches to the diagnosis and treatment of tumors of the parapharyngeal space. Head Neck Surg 1982;4: Work WP, Hybels RL. A study of tumors of the parapharyngeal space. Laryngoscope 1974;84: McIlrath D, ReMine WH, Devine KD, Dockerty MB. Tumors of the parapharyngeal region. Surg Gynecol Obstet 1963; 116: Kragh LV, Soule EH, Masson JK. Benign and malignant neurilemmomas of the head and neck. Surg Gynecol Obstet 1960;111: Gibberd GF. Two cases of neurofibroma of the cervical sympathetic. Guys Hosp Rep 1924;74: Mayo CW. Cervical neurofibroma. Surg Gynecol Obstet 1934;59: Amano M. Ueber zwei Faelle von Neurinom des Halssympathikus. Zentralbl Chir 1934;61: Callum EN. Neurinoma of cervical sympathetic chain. Br J Surg 1950;37: Cullen TH, Monro RS. Cervical neurofibroma in the differential diagnosis of carotid body tumor. Br J Surg 1952;39: Rogers L. Neurinomas of the cervical sympathetic system with report of a case. Br J Surg 1953;40: Brandt U. Neurinome du sympathique cervical. Acta Otolaryngol 1953;43: Daly JF, Roesler HK. Neurilemmoma of the cervical sympathetic chain. Arch Otolaryngol 1963;77: Clifton MA. Sympathetic neurilemmoma: an uncommon cause of solitary cervical swelling. J R Coll Surg Edinb 1977; 22: Clairmont AA, Conley JJ. Schwannoma of the cervical sympathetic nerve. Ear Nose Throat J 1978;57: Sharaki MM, Talaat M, Hamam SM. Schwannoma of the neck. Clin Otolaryngol 1982;7: Myssiorek DJ, Silver CE, Valdes ME. Schwannoma of the cervical sympathetic chain. J Laryngol Otol 1988;102: Takimoto T, Katoh H, Umeda R. Parapharyngeal schwannoma of the cervical sympathetic chain in a child. Int J Pediatr Otorhinolaryngol 1989;18: Hallet JW, Nora JD, Hollier LH, Cherry KJ, Pairolero PC. Trends in neurovascular complications of surgical management for carotid body and cervical paragangliomas: a fiftyyear experience with 153 tumors. J Vasc Surg 1988;7: Pesavento G, Ferlito A, Recher G. Benign solitary schwannoma of the cervical vagus nerve: a case report with a review of the literature. J Laryngol Otol 1979;93: