Neurilemmomas (neurilemomas) are benign, encapsulated tumors of the nerve sheath. Their cells of origin are thought to be Schwann cells derived from the neural crest (see the image below); accordingly, they are often referred to as schwannomas. These masses usually arise from the side of a nerve, are well encapsulated, and have a unique histologic pattern.
This benign lesion essentially manifests itself with cosmetic deformity, a palpable mass, symptoms similar to a compressive neuropathy, or some combination of these. 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.
The cause of these neoplasms is unknown.  Neurilemmoma can be associated with von Recklinghausen disease; when this is the case, multiple tumors often are present.
Neurilemmoma is the most common neurogenic tumor, but precise prevalence figures are not available. They affect persons aged 20-50 years. No racial or sex predilection is recognized. 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.
Recurrence is unlikely after complete resection. Patients usually have rapid and complete relief of pain, with excellent long-term results. 
Rare descriptions exist of malignant change in long-standing neurilemmomas, usually in patients with an underlying diagnosis of neurofibromatosis. Malignant change is extremely rare in isolated lesions.
Kano et al 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 (Elekta, Stockholm, Sweden) 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 Gardner-Robertson (GR) class I hearing. Patients who received a radiation dose lower 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 lower than 4.2 Gy retained serviceable hearing at 2 years after surgery.
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Ian D Dickey, MD, FRCSC, LMCC Orthopedic Surgeon, Colorado Limb Consultants, Denver Clinic for Extremities at Risk; Medical Director, Denver Sarah Cannon Sarcoma Network; Staff Surgeon, Department of Orthopedics, Presbyterian/St Luke’s Hospital; Adjunct Professor, Department of Chemical and Biological Engineering, University of Maine
Ian D Dickey, MD, FRCSC, LMCC is a member of the following medical societies: Canadian Orthopaedic Association, Maine Society of Orthopaedic Surgeons, Mayo Clinic Alumni Association, Musculoskeletal Tumor Society, New England Orthopedic Society, Royal College of Surgeons of Canada
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.
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.
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 of 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, Florida Medical Association, Florida Orthopaedic Society
Disclosure: Nothing to disclose.
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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