Management of Nerve Sheath Tumors Arising in the Sympathetic Chain

Surbhi Jain, MD; Kristin Houseknecht, MPH; Amyn M. Rojiani, MD, PhD; Matthias Setzer, MD; Frank D. Vrionis, MD, MPH, PhD

Disclosures

Cancer Control. 2008;15(4):352-357. 

In This Article

Discussion

Schwannomas were first described by Verocay in 1908.[5] Since that time, they have been called neurilemmomas, solitary nerve sheath tumors, perineural fibroblast tumors and, most recently, schwannomas, according to the World Health Organization (WHO) classification.[6,7]

Epidemiology

Schwannomas may occur sporadically or in association with syndromes such as neurofibromatosis type 2 or schwannomatosis.[5,8,9] Sympathetic chain schwannomas are rare, with fewer than 50 cases reported in the literature, and are predominately located in the cervical or lumbar retroperitoneal region.[1,2,3,5,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34] Schwannomas of the sympathetic chain occur between the ages of 30 and 70 years[34] but are most common in patients between 20 and 50 years of age.[1] The male:female ratio has been reported as 3:1.[34] No other etiologic factors or predispositions have been delineated from the small series or case reports that have been reported.

Clinical Presentation

The majority of sympathetic schwannomas are asymptomatic at the time of presentation. Sympathetic chain schwannoma may be accompanied by vague symptoms such as sore throat, hoarseness, or dysphagia in cervical region tumors and abdominal/flank pain in lumbar retroperitoneal tumors. Although schwannomas rarely compress or destroy the nerve, clinical findings related to sympathetic chain involvement may be present. The presence of Horner's syndrome before excision has been recorded in 6 previous cases of cervical schwannomas and also in our patient with cervical tumor.[10,18,19,26,27,28,29,30,32,34] Histopathologically, there appeared to be nothing to distinguish the patient presenting with Horner's syndrome from the other patients who did not have this syndrome. In contrast, sympathetic hyperactivity has also been described in association with sympathetic schwannoma; one report describes a cervical sympathetic chain schwannoma presenting with ipsilateral lacrimation, hyperhidrosis, conjunctival injection, and nasal congestion.[12]

Diagnosis

The most challenging aspect of treating these lesions is distinguishing the benign sympathetic schwannoma from other pathologic processes with similar findings and presentations. Differential diagnosis depends on location of the mass and may include carotid artery lesions, paragangliomas, spindle cell sarcomas, or sympathetic chain neurogenic lesions. Retroperitoneal schwannomas may mimic renal or adrenal tumors or adnexal masses. Clinical examination may be helpful, but surgical intervention is often required to arrive at a definitive diagnosis and to exclude malignancy. Histopathology and immunohistochemistry are essential in diagnosis.

MRI has been shown to demonstrate high signal intensity on T2-weighted images, with relatively low signal intensity on T1-weighted images. In contrast with paragangliomas, there are no vascular flow voids in schwannomas. In general, schwannomas are hypodense compared with muscle on CT scan without contrast. When contrast is added, some degree of enhancement may be present. In paracervical schwannomas, direct visualization with ultrasound has been described as useful in differentiating vagus nerve schwannoma from sympathetic chain schwannoma.[17] Carotid angiogram may also be useful in evaluating paracervical tumors; while hypervascularity is characteristic in carotid body tumors, schwannomas lack hypervascularity.[25,27,33] Due to the compartmentalization of the cervical region, it is possible to suspect a diagnosis based on the anatomical region. In comparison to schwannomas,paragangliomas usually have a more cranial origin in the lateral cervical region. Schwannomas may have their origin in the parapharyngeal space, including cranial nerves IX, X, XI, and XII. Schwannomas of the vagus nerve grow between the common carotid artery and the internal jugular vein. This growth pattern often leads to a divergence of both structures, which is visible in CT scan or MRI. Furthermore, these tumors tend to be vascular; schwannomas of the sympathetic chain do not cause this separation of the common carotid artery and the internal jugular vein and are not typically vascular tumors.[1]

Histopathology

As noted earlier, histopathology and immunohistochemistry are essential in establishing the diagnosis. The WHO classification of tumors of the central nervous system categorizes the schwannomas (synonymous: neurilemmoma, neurinoma) under tumors of cranial and paraspinal nerves. The classification differentiates between cellular, plexiform, and melanotic subtypes.[6,7] Immunohistochemistry in schwannomas is characteristically positive for S-100 and negative for neurofilament protein.[35]

Treatment

The issue of watchful waiting vs surgical resection is debated in clinical practice. However, there are several reasons to prefer a surgical resection. First, sympathetic chain schwannoma patients in our series and reported in the literature are young (20 to 50 years)[1] and have a life expectancy of several decades, which means that even currently asymptomatic tumors will finally grow to a size that will cause problems. Second, as already noted, there are several differential diagnoses to consider, some of which require more urgent surgical resection (eg, sarcomas, lung carcinomas). Since sympathetic chain ganglia schwannomas are rare, it is more likely for a cervical or thoracic paraspinal lesion to belong to the aforementioned category. Third, schwannomas may be or may become malignant in rare cases and require adjuvant therapies. Therefore, it is important to obtain a reliable histologic diagnosis. In summary, these points illustrate the frequent need of a surgical resection vs long-term surveillance. The surgical approach to the paravertebral space is well known and within the armamentarium of all spine surgeons and neurosurgeons. All vascular structures and neural structures should be identified and preserved. The entrance and exit of the sympathetic nerve inferiorly and superiorly to the mass are isolated. In all of our cases, the nerve could not be preserved or dissected free from the tumor; the nerve was excised with a superior and inferior cuff. Postoperative complications involved with removing the cervical sympathetic chain commonly include Horner's syndrome,as detailed previously, as well as first bite syndrome.[19,26,34] First bite syndrome is described as pain that is worst with the first bite of a meal and is related to hypersensitivity resulting from sympathetic denervation of the parotid gland.[34] In our patient with a cervical sympathetic chain tumor, Horner's syndrome was present preoperatively but did not require intervention, and first bite syndrome was not reported.

Postoperative Morbidity

The most common complications after resection of a sympathetic chain schwannoma of the cervicothoracic region are Horner's syndrome and facial anhydrosis of the contralateral side. The ptosis is due to the paralysis of Mueller's muscle and can be treated by advancement of the levator aponeurosis or by resection of the conjunctiva and Mueller's muscle.[1,36] In our series,Horner's syndrome in the patient with the C7-T1 sympathetic chain schwannoma persisted after surgery. Typically, this syndrome is not debilitating as it does not alter vision but primarily affects cosmetic appearance.

Comments

3090D553-9492-4563-8681-AD288FA52ACE
Comments on Medscape are moderated and should be professional in tone and on topic. You must declare any conflicts of interest related to your comments and responses. Please see our Commenting Guide for further information. We reserve the right to remove posts at our sole discretion.

processing....