Cervical ganglioneuroma mimicking a carotid body tumour

Abstract

A 30-year-old woman was referred to the ear, nose and throat clinic by her primary care physician for a 10-year history of an asymptomatic, large, right-sided neck mass. On examination, the patient had a palpable, non-tender, five-by-four centimetre, mobile, right-sided level II neck mass. CT scan with intravenous contrast showed an enhancing mass with multiple fluid cavities, splaying the external carotid and internal carotid arteries, concerning for a carotid body tumour. Patient was then referred to interventional radiology for angiography and embolisation prior to definitive surgical excision. However, when the mass was then excised surgically, final pathology identified the mass as a ganglioneuroma. Patient recovered well postoperatively with some ptosis of the right eye and symptoms consistent with first bite syndrome, treated with conservative measures.

Background

Ganglioneuromas are classified as part of the neuroblastic tumour family. They are primarily composed of Schwann and ganglion cells. These benign tumours are commonly found in the retroperitoneum, adrenal glands and posterior mediastinum.¹ They are commonly seen in the paediatric population, but the age of presentation can vary. Patients present with an asymptomatic neck mass or display symptoms related to catecholamine release from the tumours including diarrhoea, headaches and palpitations.² The patient described in this report was unique due to the location of their ganglioneuroma and the clinical similarity to a carotid body tumour.

Case presentation

A 30-year-old Caucasian woman presented to the ear, nose and throat (ENT) clinic with an asymptomatic right-sided neck mass. She reported having it for approximately 10 years without significant change in size. On examination, she had a palpable, mobile mass in the right neck level II that was non-tender to palpation. The mass was pulsatile in nature and measured approximately five-by-four centimetres in size. She had neither voice changes nor difficulty breathing, dysphagia or syncope. She was normotensive and had normal vital signs. Her review of systems was otherwise negative. Her past medical history and surgical history were unremarkable. She denied any use of tobacco, alcohol, or illicit substances. Family history was unremarkable for any history of cancer.

Investigations

Initial CT scan with intravenous contrast showed an enhancing mass with multiple fluid cavities, splaying the external carotid (EAC) and internal carotid (IAC) arteries, concerning for a carotid body tumour (figure 1). The patient then underwent MRI with and without intravenous contrast of the neck. T1-weighted images showed the mass to be hypointense compared with surrounding muscle and the mass was noted to enhance with contrast. Evidence of flow voids was noted with a ‘salt and pepper’ appearance (figure 2). T2-weighted images showed the mass to be hyperintense compared with muscle. Given what appeared to be the vasculature nature of the mass, the patient was referred to interventional radiology for angiography and possible embolisation prior to surgical excision. Further imaging and angiography were performed, which revealed a tumour that was attached to the skull base superiorly with roughly 80% of the vascularisation of the mass being derived from a branch of the right ascending pharyngeal artery that was then successfully embolised. This initial workup was therefore most concerning for a carotid body tumour.

Figure 1.

Contrast-enhanced CT images of the patient demonstrate a 5.0×4.0 cm right carotid body tumour. The mass appears to extend from the external carotid artery to the internal carotid artery.

Figure 2.

T2-weighted MRI images of the patient demonstrate a hyperintensive, ‘salt and pepper’ appearance to the mass suggesting a right carotid body tumour.

Differential diagnosis

Differential diagnoses included paraganglioma, thyroid mass, head and neck carcinoma, lymphoma, schwannoma and ganglioneuroma, neurofibroma, and salivary tumours. Paragangliomas, or carotid body tumours, are found between the IAC and EAC arteries near the base of the skull. These patients tend to be asymptomatic but may secrete catecholamines, resulting in similar symptoms to ganglioneuromas.

Patients with a thyroid mass may also be asymptomatic or present with dysphagia, hoarseness and difficulty breathing. These patients may present with normal or abnormal thyroid levels. The majority of head and neck cancers are squamous cell carcinoma. Patients with head and neck cancer may present with a wide range of symptoms ranging from throat pain, otalgia, hoarseness, cough, trouble eating, or difficulty breathing. Patients with lymphoma often initially present with cervical lymphadenopathy and B symptoms (fever, weight loss and night sweats). Neurofibromas are benign tumours that can be cutaneous or intraneural. Malignant neurofibromas are associated with Neurofibromatosis type 1. Patients can present with a painless, growing mass. However, when they involve nerves, they may present with nerve palsies (eg, facial nerve palsy). Salivary tumours are commonly benign neoplasms. Malignant salivary tumours are usually symptomatic, causing a variety of symptoms such as pain and nerve palsies. Most patients with a schwannoma are asymptomatic. However, depending on the location of the schwannoma, patients may have sensory loss and weakness. Schwannomas and ganglioneuromas are neurogenic tumours that differ in their morphologies. Like schwannomas, ganglioneuromas tend to be slow growing as in our patient’s case. However, given the pulsatile nature along with the classic preoperative imaging findings, paraganglioma remained highest on the differential. After discussion of the differential diagnoses and treatment option, the patient elected to pursue surgical resection of the mass.

Treatment

Surgical resection was conducted under general anaesthesia. After raising the subplatysmal flaps and retracting the sternocleidomastoid muscle laterally, the large mass was noted to be displacing the internal jugular vein laterally and closely associated with the carotid bifurcation. However, after careful dissection, it was noted that the mass itself was not adherent to the carotid artery. It appeared to be originating from the sympathetic chain. The tumour was then removed after multiple feeding vessels, including the ascending pharyngeal artery, which were ligated. The specimen was sent for permanent pathology and the procedure was completed without any apparent complications.

Outcome and follow-up

Patient was monitored in the hospital postoperatively without incident. She reported mild right auricular numbness, but otherwise denied problems with her voice, breathing, or eating. Physical examination revealed no facial weakness or asymmetry. She ambulated without difficulty or dizziness and her surgical drain was removed prior to her discharge on postoperative day 2. The patient continued to recover at home and was seen in clinic postoperatively where pathology was discussed. She was subsequently noted to have mild right-sided ptosis and pain on first bite of food that has been treated with conservative measures. Postoperative visit on week 12 revealed no evidence of recurrence of the mass. Due to her continued symptoms of first bite syndrome, she was started on the neuromodulator pregabalin (lyrica) to treat her symptoms, with plans to continue monitoring for resolution.

Discussion

Ganglioneuromas are benign, slow-growing tumours that are typically asymptomatic, until they impinge on neighbouring structures in the neck. Malignant transformation is a rare occurrence in patients with ganglioneuromas. They are well differentiated, well circumscribed and encapsulated tumours derived from the central or peripheral nervous system.³ Their main components consist of Schwann cells (S100 protein positive) and ganglion cells.³ Histologically, they contain an abundant amount of cytoplasm, large nuclei and prominent nucleoli.³ On MRI, ganglioneuromas are T1 hypointense and T2 hyperintene compared with muscle, with a salt and pepper appearance.¹

Parapharyngeal space tumours can usually be differentiated by appearance by using MRI. Schwannomas are T1 hypointense and T2 hyperintense with possible bleeding or necrosis.¹ Neurofibromas are T1 hypointensive and present on T2 with a target sign (hyperintensive outside, hypointensive inside).⁴

Ganglioneuromas are often associated with syndromes like neurofibromatosis and multiple endocrine neoplasia 2b.⁵ Ganglioneuromas in the gastrointestinal tract are often associated with these syndromes.⁵ However, they are most commonly found in the retroperitoneum, adrenal glands, and posterior mediastinum.¹ Less than 8% of ganglioneuromas are located in the neck.⁶ Patients with ganglioneuromas are treated and cured by surgical excision, but this often comes with the slight risk of iatrogenic postoperative complications. Our patient was unique due to the location and size of her tumour as well as the diagnostic similarity to a carotid body tumour.

One case report in the literature discussed a 17-year-old man with a parapharyngeal ganglioneuroma. This patient presented with 1-week history of throat pain and dysphagia.⁷ Another case report discussed a 41-year-old woman with a cervical ganglioneuroma. This patient presented with Brown-Sequard syndrome for several weeks.⁸ Brown-Sequard syndrome occurs due to hemisectional injury to the spinal cord. Patients present with ipsilateral loss of vibratory sense and proprioception and contralateral loss of pain, temperature and light touch. Similarly, another case report was of a 32-year-old man with a 1-year history of an asymptomatic, left-sided neck mass.¹ All three patients were successfully treated by surgical excision.

In the case of our patient, the ability to differentiate between a paraganglioma and ganglioneuroma was obscured, requiring histological analysis for final confirmation. Both tumours can be slow-growing masses that are usually non-functional when located in the head and neck region. On MRI, they can be T1 hypointense and T2 hyperintense with a ‘salt and pepper’ appearance, which could be as a result of internal haemorrhages.⁹ In fact, about 80% of paragangliomas can be identified on T2 MRI due to reduced signal intensity from internal haemorrhage and flow voids.⁹

There are several postoperative complications that are generally expected that were seen in our patient: first bite syndrome, postoperative auricular numbness, and Horner’s syndrome. First bite syndrome is thought to occur due to damage of nerve fibres from the sympathetic cervical chain.¹⁰ Patients initially experience pain in the parotid region of their face with their first bite of food, symptoms may be treated with neuromodulator drugs, like pregabalin.¹⁰ Postoperative auricular numbness is often caused by disruption of the great auricular nerve, derived from C2 and C3 nerve roots.¹¹ This is often transient, as with the patient described in this case report. Patient’s with Horner’s typically present with ipsilateral ptosis, miosis, and anhidrosis.¹² In the case of our patient, she only presented with ipsilateral ptosis. Symptomatic treatment includes usage of an alpha-adrenergic agonist, such as apraclonidine, which helps elevate the upper eyelid.¹²

Learning points.

• Ganglioneuromas are predominantly made up of ganglion cells and Schwann cells.

• Ganglioneuromas are uncommonly found in the head and neck region.

• Ganglioneuromas in the neck can closely mimic paragangliomas.