title: Long-term progression of lipomatosis of nerve.
abstract: OBJECTIVE
  Lipomatosis of nerve (LN) is a condition of massive peripheral nerve enlargement due to proliferation of fibrous and adipose tissue within the nerve, the natural history of which is currently unknown. We measured the pattern of growth in individuals with long-term radiologic follow-up.
  
  
  METHODS
  Review of the searchable records for LN at our institution found 52 patients, confirmed by pathology or pathognomic appearance on MRI. Ten patients had serial MRI of the same anatomic region for more than 2 years of clinical follow-up. Volumetric analysis was performed using regions of interest on serially imaged segments of affected nerves. Adjustment for skeletal growth was performed for pediatric patients.
  
  
  RESULTS
  LN enlarged in 7 of 10 individuals, often both longitudinally along the nerve and in cross-sectional volume. Regarding cross-sectional volume, 2 of the 10 patients demonstrated volume growth more than doubling and 5 additional patients had a >20% increase in nerve volume; the remaining 3 patients were quiescent, where change in the nerve volume was within the error range of volumetric analysis. All cases with growth remained >20% after adjustment for skeletal growth. Five of 10 individuals had longitudinal extension, even with correction for skeletal growth. More significant growth was noted in younger patients (P=0.02). Growth rates more than 5% per year correlated with surgery, without statistical significance in this small population (P=0.14).
  
  
  CONCLUSIONS
  Serial MRI reveals progressive enlargement of LN. The rate of growth was more profound in youth, but also occurred in early adulthood.
authors.affiliation: Barrow Neurological Institute, Phoenix, Arizona, USA.
authors.forename: Mark A
authors.initials: MA
authors.lastname: Mahan
authors.affiliation: Department of Radiology, Mayo Clinic, Rochester, Minnesota, USA.
authors.forename: Blake D
authors.initials: BD
authors.lastname: Niederhauser
authors.affiliation: Department of Neurologic Surgery, Mayo Clinic, Rochester, Minnesota, USA; Department of Radiology, Mayo Clinic, Rochester, Minnesota, USA.
authors.forename: Kimberly K
authors.initials: KK
authors.lastname: Amrami
authors.affiliation: Department of Neurologic Surgery, Mayo Clinic, Rochester, Minnesota, USA; Department of Orthopedics, Mayo Clinic, Rochester, Minnesota, USA. Electronic address: spinner.robert@mayo.edu.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Spinner
mesh_terms: D000293:Adolescent; D000328:Adult; D017668:Age of Onset; D000375:Aging / Q000473:pathology; D019412:Anatomy, Cross-Sectional; D002349:Carpal Tunnel Syndrome / Q000209:etiology / Q000601:surgery; D002648:Child; D002675:Child, Preschool; D018450:Disease Progression; D006801:Humans; D008068:Lipomatosis / Q000150:complications / Q000473:pathology* / Q000601:surgery; D008137:Longitudinal Studies; D008279:Magnetic Resonance Imaging; D019635:Neurosurgical Procedures; D010523:Peripheral Nervous System Diseases / Q000150:complications / Q000473:pathology* / Q000601:surgery; D055815:Young Adult
keywords: Fibrolipomatous hamartoma; Lipofibromatous hamartoma; Lipomatosis of nerve; Macrodactyly; Macrodystrophia lipomatosa; Peripheral nerve; Volumetric