Introduction
Neurilemmomas are benign, encapsulated tumors of the nerve sheath. Their cells of origin are thought to be Schwann cells derived from the neural crest. These masses usually arise from the side of a nerve, are well encapsulated, and have a unique histologic pattern.
Images of neurilemmoma are provided below:
The cell of origin for a neurilemmoma is the Schwann cell, which is derived from the neural crest. These cells line the peripheral nerve processes.
Neurilemmomas have very distinctive appearances on magnetic resonance images. Many investigators believe that the presence of a target sign on a peripheral nerve is diagnostic for a neurilemmoma.
Pathology specimen.
Recent studies
Tan et al assessed the trends in management of unilateral vestibular schwannoma at Johns Hopkins University from 1997-2007 and found that there was an increase in cases observed with follow-up scanning (10.5% to 28.0%) and recommended for radiation (0% to 4.0%), while there was a decrease in surgical cases (89.5% to 68.0%). They noted that the increased frequency of observation relative to surgery was significant even after controlling for age, hearing status, and tumor size. The authors concluded that the changing trend implied a change in both provider philosophy and expectations of patients.1
Kano et al of the University of Pittsburgh evaluated tumor control and hearing preservation relating to tumor volume, imaging characteristics, and nerve and cochlear radiation dose after stereotactic radiosurgery with a Gamma Knife in patients with acoustic neuroma. At a median of 20 months after surgery, none of the patients required further treatment. Serviceable hearing was preserved in 71% of all patients and in 89% of patients with GR (Gardner-Robertson) class I hearing. Patients who received a radiation dose less than 4.2 Gy to the central cochlea had significantly better hearing preservation of the same GR class, and all 12 patients younger than 60 years who received a cochlear radiation dose less than 4.2 Gy retained serviceable hearing at 2 years after surgery.2
Problem
The benign lesion essentially manifests itself with cosmetic deformity, a palpable mass, and/or symptoms similar to a compressive neuropathy. Neurologic symptoms tend to present late. Symptoms can be vague, and there is an average interval of up to 5 years before the diagnosis is established. Neurilemmoma is the most common neurogenic tumor.
Frequency
The prevalence of these benign lesions is unknown.
Etiology
The cause of these neoplasms is unknown.3 Neurilemmoma can be associated with von Recklinghausen disease; when this is the case, multiple tumors often are present.
Presentation
No racial or sex predilection is recognized. Neurilemmomas affect persons aged 20-50 years. Common locations for the tumors are, in order of decreasing frequency, the head and flexor surfaces of the upper and lower extremities and the trunk. The mass is usually mobile in the transverse plane and tethered along the axis of the nerve from which it arises.
Tenderness to palpation is often present; secondary neurologic symptoms may occur if the tumor is large. When involving the C7 nerve root, neurilemmoma has been described as a cause of thoracic outlet syndrome. Lesions in the sciatic nerve can mimic discogenic low-back pain.
Differential diagnoses include the following:
Indications
Neurilemmomas can cause a functional deficit because of local pressure on the nerve of origin. Malignant degeneration, which is extremely rare, was described by Yousem and colleagues in 1985.4 Primary malignant tumors of this cell type do exist, but they are histologically distinct from neurilemmomas.
Relevant Anatomy
Because these tumors can present in many locations, the clinical presentation can be varied.5 Some may involve the spinal nerve roots and present with symptoms that mimic those of herniated disk disease of the spine.6,7 In the extremities, neurilemmomas can present either as an asymptomatic mass or as mild, localized pain and paresthesia resulting from pressure on the nerve of origin. Masses are slow growing and can exist for months to years without producing symptoms. The average time from onset of symptoms to diagnosis is 5.5 years.
Lesions in proximal nerves may cause distal symptoms. If these masses occur in well-defined compartments (eg, wrist, ankle), they can present as either carpal tunnel or tarsal tunnel syndrome.
Contraindications
In an unusual case in which resection would lead to a significant functional deficit, these benign lesions can be merely observed.
More on Neurilemmoma |
 Overview: Neurilemmoma |
| Workup: Neurilemmoma |
| Treatment: Neurilemmoma |
| Follow-up: Neurilemmoma |
| Multimedia: Neurilemmoma |
| References |
| Further Reading |
| Next Page » |
References
Tan M, Myrie OA, Lin FR, Niparko JK, Minor LB, Tamargo RJ, et al. Trends in the management of vestibular schwannomas at Johns Hopkins 1997-2007. Laryngoscope. Jan 2010;120(1):144-9. [Medline].
Kano H, Kondziolka D, Khan A, Flickinger JC, Lunsford LD. Predictors of hearing preservation after stereotactic radiosurgery for acoustic neuroma. J Neurosurg. Oct 2009;111(4):863-73. [Medline].
Roche PH, Bouvier C, Chinot O, Figarella-Branger D. Genesis and biology of vestibular schwannomas. Prog Neurol Surg. 2008;21:24-31. [Medline].
Yousem SA, Colby TV, Urich H. Malignant epithelioid schwannoma arising in a benign schwannoma. A case report. Cancer. Jun 15 1985;55(12):2799-803. [Medline].
Guerrissi JO. Solitary benign schwannomas in major nerve systems of the head and neck. J Craniofac Surg. May 2009;20(3):957-61. [Medline].
Bakar B, Sumer MM, Cila A, Tekkok IH. An extreme lateral lumbar disc herniation mimicking L4 schwannoma. Acta Neurol Belg. Jun 2009;109(2):155-8. [Medline].
Ichinose T, Takami T, Yamamoto N, Tsuyuguchi N, Ohata K. Intratumoral hemorrhage of spinal schwannoma of the cauda equina manifesting as acute paraparesis--case report. Neurol Med Chir (Tokyo). Jun 2009;49(6):255-7. [Medline].
Fortnum H, O'Neill C, Taylor R, Lenthall R, Nikolopoulos T, Lightfoot G, et al. The role of magnetic resonance imaging in the identification of suspected acoustic neuroma: a systematic review of clinical and cost effectiveness and natural history. Health Technol Assess. Mar 2009;13(18):iii-iv, ix-xi, 1-154. [Medline].
Kida Y, Yoshimoto M, Hasegawa T. Radiosurgery for facial schwannoma. J Neurosurg. Jan 2007;106(1):24-9. [Medline].
Rutten I, Baumert BG, Seidel L, et al. Long-term follow-up reveals low toxicity of radiosurgery for vestibular schwannoma. Radiother Oncol. Jan 2007;82(1):83-9. [Medline].
Sade B, Mohr G, Dufour JJ. Vascular complications of vestibular schwannoma surgery: a comparison of the suboccipital retrosigmoid and translabyrinthine approaches. J Neurosurg. Aug 2006;105(2):200-4. [Medline].
Strauss C, Prell J, Rampp S, et al. Split facial nerve course in vestibular schwannomas. J Neurosurg. Nov 2006;105(5):698-705. [Medline].
Kondziolka D, Lunsford LD. Future perspectives in acoustic neuroma management. Prog Neurol Surg. 2008;21:247-54. [Medline].
Pillai P, Sammet S, Ammirati M. Image-guided, endoscopic-assisted drilling and exposure of the whole length of the internal auditory canal and its fundus with preservation of the integrity of the labyrinth using a retrosigmoid approach: a laboratory investigation. Neurosurgery. Dec 2009;65(6 Suppl):53-9; discussion 59. [Medline].
Beggs I. Pictorial review: imaging of peripheral nerve tumours. Clin Radiol. Jan 1997;52(1):8-17. [Medline].
Belding RH. Neurilemoma of the lateral plantar nerve producing tarsal tunnel syndrome: a case report. Foot Ankle. Jun 1993;14(5):289-91. [Medline].
Campanacci M. Bone and Soft Tissue Tumors: Clinical Features, Imaging, Pathology and Treatment. 2nd ed. New York, NY: Springer-Verlag; 1999.
Cerofolini E, Landi A, DeSantis G, et al. MR of benign peripheral nerve sheath tumors. J Comput Assist Tomogr. Jul-Aug 1991;15(4):593-7. [Medline].
Idler RS. Benign and malignant nerve tumors. Hand Clin. May 1995;11(2):203-9. [Medline].
Mikami Y, Hidaka T, Akisada T, et al. Malignant peripheral nerve sheath tumor arising in benign ancient schwannoma: a case report with an immunohistochemical study. Pathol Int. Feb 2000;50(2):156-61. [Medline].
Stull MA, Moser RP, Kransdorf MJ, et al. Magnetic resonance appearance of peripheral nerve sheath tumors. Skeletal Radiol. 1991;20(1):9-14. [Medline].
Woodruff JM, Selig AM, Crowley K, et al. Schwannoma (neurilemoma) with malignant transformation. A rare, distinctive peripheral nerve tumor. Am J Surg Pathol. Sep 1994;18(9):882-95. [Medline].
Further Reading
Related eMedicine topics
Neurilemmoma (Dermatology)
Skull Base, Acoustic Neuroma (Vestibular Schwannoma)
Schwannoma, Cranial Nerve
Gamma Knife and Other Stereotactic Radiotherapies for Acoustic Neuroma
Keywords
neurilemmoma, neurilemoma, schwannoma, neurinoma, nerve sheath tumor, Schwann cell tumor, neuroschwannoma, acoustic neuroma, vestibular schwannoma
