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Neurilemmoma Workup

  • Author: Ian D Dickey, MD, FRCSC; Chief Editor: Harris Gellman, MD  more...
Updated: Nov 21, 2014

Imaging Studies

Findings on plain radiography generally are not specific. The rare intraosseous lesion presents as a benign-appearing, well-circumscribed lesion. Differential diagnoses for these lesions include giant cell tumors, chordomas (when involving the spine), and chondroblastomas. Massive bony destruction may be present, especially when the lesion involves the sacrum.

Special studies to consider are those employing computed tomography (CT) scanning or magnetic resonance imaging (MRI). MRI is particularly useful (see the image below); it shows a usually round or oval mass with a moderately bright signal on T1-weighted images and a bright, heterogeneous signal on T2-weighted images.[5] The mass is usually less than 2.5 cm in size. The lesion enhances uniformly with gadolinium contrast.

Neurilemmomas have very distinctive appearances on 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.

Wu et al conducted a study to determine the value of ultrasonography in the diagnosis of neurilemmoma and to determine whether the presence of a round or roundlike shape on the ultrasound image is diagnostically useful.[6] They concluded that ultrasonography is capable of diagnosing neurilemmomas with a high degree of accuracy but that round or roundlike shape and the ratio of longitudinal maximal diameter to short maximal diameter (L/S) are of little value in identifying neurilemmomas of the limbs.


Diagnostic Procedures

Biopsy may be needed to clearly define the tissue type. For bone lesions and for particularly large soft-tissue lesions, biopsy is prudent to ensure correct diagnosis and management. Whenever a biopsy is considered, strict biopsy guideline principles must be followed.


Histologic Findings

Lesions of the spinal cord often have a dumbbell shape; otherwise, they are fusiform in shape. They have an epineurium encapsulation, frequently with overlying vessels. The cut surface is pink or white. In very large masses, degenerative cysts, hemorrhage, or dystrophic calcification may be present.

Neurilemmomas have a well-defined, fibrous capsule. Histologically, there are two distinct regions, as follows:

  • Antoni A areas - These are cellular regions with predominantly benign spindle cells in many intersecting bundles; they may palisade around eosinophilic regions that are called Verocay bodies, and they are positive for S100 staining
  • Antoni B areas - These are much less cellular and have a background of loose connective tissue that is myxomatous in appearance

Occasionally, a more aggressive histologic appearance may predominate, but such forms usually lack mitotic figures.



Neurilemmomas are commonly classified according to the Enneking system for benign lesions, as follows:

  • Grade 1 - These lesions are inactive
  • Grade 2 - These lesions deform the surrounding tissues but are not destructive or locally aggressive
  • Grade 3 - These lesions are locally aggressive and may invade local tissues but do not have metastatic potential

Generally, neurilemmomas are grade 2 or 3.


Laboratory Studies

Laboratory studies generally are not beneficial.

Contributor Information and Disclosures

Ian D Dickey, MD, FRCSC Adjunct Professor, Department of Chemical and Biological Engineering, University of Maine; Consulting Staff, Adult Reconstruction, Orthopedic Oncology, Department of Orthopedics, Eastern Maine Medical Center

Ian D Dickey, MD, FRCSC is a member of the following medical societies: American Academy of Orthopaedic Surgeons, Royal College of Physicians and Surgeons of Canada, British Columbia Medical Association, Canadian Medical Association

Disclosure: Received consulting fee from Stryker Orthopaedics for consulting; Received honoraria from Cadence for speaking and teaching; Received grant/research funds from Wright Medical for research; Received honoraria from Angiotech for speaking and teaching; Received honoraria from Ferring for speaking and teaching.


James Gerald Floyd, MD Assistant Professor, Department of Surgery, Division of Orthopedic Surgery, University of Alabama at Birmingham School of Medicine

James Gerald Floyd, MD is a member of the following medical societies: American Academy of Orthopaedic Surgeons, American Medical Association, American Orthopaedic Foot and Ankle Society, National Medical Association

Disclosure: Nothing to disclose.

Specialty Editor Board

Francisco Talavera, PharmD, PhD Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Received salary from Medscape for employment. for: Medscape.

Sean P Scully, MD 

Sean P Scully, MD is a member of the following medical societies: American Academy of Orthopaedic Surgeons, International Society on Thrombosis and Haemostasis, Society of Surgical Oncology

Disclosure: Nothing to disclose.

Chief Editor

Harris Gellman, MD Consulting Surgeon, Broward Hand Center; Voluntary Clinical Professor of Orthopedic Surgery and Plastic Surgery, Departments of Orthopedic Surgery and Surgery, University of Miami, Leonard M Miller School of Medicine, Clinical Professor, Surgery, Nova Southeastern School of Medicine

Harris Gellman, MD is a member of the following medical societies: American Academy of Medical Acupuncture, American Academy of Orthopaedic Surgeons, American Orthopaedic Association, American Society for Surgery of the Hand, Arkansas Medical Society

Disclosure: Nothing to disclose.

Additional Contributors

Howard A Chansky, MD Associate Professor, Department of Orthopedics and Sports Medicine, University of Washington Medical Center

Howard A Chansky, MD is a member of the following medical societies: American Academy of Orthopaedic Surgeons

Disclosure: Nothing to disclose.

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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.
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