Soft tissue
Adipose tissue
Lipomatosis of nerve

Author: Charanjeet Singh, M.D. (see Authors page)

Revised: 4 August 2016, last major update June 2012

Copyright: (c) 2002-2016, PathologyOutlines.com, Inc.

PubMed Search: Lipomatosis [title] nerve

Definition / General
  • Infiltration of epineurium of a major nerve by adipose and fibrous tissue
Terminology
  • Also called fibrolipoma of nerve, fibrolipomatous hamartoma of nerve, macrodystrophia lipomatosa
Epidemiology
  • May be noted at birth
  • Almost always age 30 years or less
  • Associated with macrodactyly (abnormal enlargement of digits) innervated by affected nerve in 30 - 67%
Sites
  • 85% have involvement of median nerve and its digital branches in hand, wrist and forearm (Histopathology 1994;24:391)
  • Also ulnar nerve
Radiology Description
  • T1 weighted images on MR imaging reveal a fatty mass that is evenly distributed between nerve bundles and is seen running along individual nerves
  • Often described as having a "coaxial cable-like" appearance on axial scans (Acta Radiol 2003;44:326)
Case Reports
Treatment
  • Benign but often no effective treatment as resection causes sensory and motor deficits (J Neurosurg 1998;89:683)
  • Carpal tunnel release may relieve symptoms of median nerve involvement
  • Amputation if severe deformity
  • May recur in 33 - 60% if incomplete resection
Clinical Images

Images hosted on PathOut servers:

X-ray, courtesy of Mark R. Wick, M.D.



Images hosted on other servers:

Median nerve

Figure 8c:
Lipomatosis of
the median nerve
in a patient with
macrodactyly

Figure 9a:
Lipomatosis of
the median nerve
in a patient without
macrodactyly

Gross Description
  • Fusiform enlargement of nerve by yellow adipose tissue, confined within epineurium
Gross Images

Images hosted on other servers:

Figure 8d:
Lipomatosis of
the median nerve
in a patient with
macrodactyly

Figure 9c:
Lipomatosis of
the median nerve
in a patient without
macrodactyly

Micro Description
  • Infiltration of epineurium and perineurium by adipose and fibrous tissue (collagen), causing enlargement of nerve
  • Concentric perineurial fibrous tissue and pseudo-onion bulb formation
  • Occasionally metaplastic bone
Micro Images

Images hosted on PathOut servers:

Courtesy of Mark R. Wick, M.D.

Case of the Week #158



Images hosted on other servers:

Figure 9d:
Lipomatosis of
the median nerve
in a patient without
macrodactyly

Figure 11c:
Angiolipoma in the
subcutaneous thigh
of a 21 year old man

Lipoma of nerve



Courtesy of Saroona Haroon, M.D.

Differential Diagnosis