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Fibroproliferative Neuromas May Occur After Iatrogenic Injury for Lipomatosis of Nerve

Mahan, Mark A. MD*; Amrami, Kimberly K. MD§; Spinner, Robert J. MD‡,¶

doi: 10.1227/01.neu.0000430289.93304.e5
Research-Human-Clinical Studies

BACKGROUND: Lipomatosis of nerve (LN) is a condition associated with nerve-territory overgrowth. We have noted a unique type of neuroma at sites of LN injury; the neuroma extends beyond the epineurium, enhances, and appears to enlarge over time.

OBJECTIVE: We sought to understand the relationship between fibroproliferative scarring and surgery performed on the nerve.

METHODS: A review of the searchable records for LN at our institution found 52 cases, confirmed by pathology or pathognomonic appearance on magnetic resonance imaging (MRI). Clinical histories were reviewed to categorize the surgeries performed by the degree of iatrogenic injury to the nerve. Postoperative MRI was performed in 22 of the 46 patients who had surgery, which was then retrospectively reviewed for fibroproliferative neuromas.

RESULTS: Complex and masslike neuromas were found on MRI, correlating with the degree of iatrogenic injury to the nerve. These fibrous neuromas proliferated beyond the epineurium, disrupted fascicular architecture, were contrast enhancing when contrast was administered, indicative they were unique and unlike stump or traction neuromas. Of the 8 patients who underwent surgery involving nerve decompression alone, none developed fibroproliferative neuromas. Of the 7 patients who underwent surgery involving nerve debulking, fibroproliferative neuromas developed in 4. Of the 11 patients who underwent surgery involving nerve transection, all developed fibroproliferative neuromas (P < .001). There was also a high incidence of hypertrophic scarring of the skin incision (21.3%).

CONCLUSION: Surgical injury of LN appears to be strongly associated with the development of fibroproliferative neuromas. It is possible that the pathological overgrowth stimulus associated with LN promotes exuberant scar formation.

ABBREVIATION: LN, lipomatosis of nerve

*Division of Neurological Surgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona;

Departments of Neurologic Surgery,

§Radiology, and

Orthopedics, Mayo Clinic, Rochester, Minnesota

Correspondence: Robert J. Spinner, MD, Mayo Clinic, Gonda 8-214, Rochester, MN 55905. E-mail:

Received December 14, 2012

Accepted March 20, 2013

Copyright © by the Congress of Neurological Surgeons