Soft tissue
Peripheral nerve
Plexiform neurofibroma

Author: Vijay Shankar, M.D. (see Authors page)

Revised: 19 September 2016, last major update November 2012

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

PubMed Search: Plexiform neurofibroma [title]

Cite this page: Plexiform neurofibroma. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/softtissueneurofibromaplexiform.html. Accessed December 4th, 2016.
Definition / General
  • Benign peripheral nerve sheath tumor that surrounds multiple nerve fascicles
  • Has irregularly thickened, distorted, tortuous structure
  • Plexiform: complex; in the form of a plexus or network
Sites
  • Orbit, face, neck, back, inguinal
Clinical Features
  • Almost always develops during childhood
  • Large tumors are attached to major nerve trunks in neck or extremities
  • 5% transform to MPNST, a higher rate than classic neurofibromas
  • Part of diagnostic criteria for neurofibromatosis type 1 (NF1, Mod Pathol 1998;11:612), although isolated plexiform neurofibromas may occur without definitive evidence of NF1 (Laryngoscope 2004;114:1410)
  • 27% of childhood neurofibroma patients had plexiform neurofibromas in one study (J Pediatr (Rio J) 2007;83:571)
Case Reports
Treatment
  • Excision for symptomatic relief; often cannot completely excise the tumor
  • Recurrence may occur even if completely excised
Clinical Images

Images hosted on PathOut servers:

NF1 patient, courtesy of Mark R. Wick, M.D.



Images hosted on other servers:

7 year old girl with cafe au lait spots; mother (right) had small neurofibroma

Cutaneous neurofibroma various locations

Heterogeneous mass of the left submandibular gland

Mass with diffuse heterogeneous enhancement



Large mass on back - pre and post op

12 year old boy with swelling of the face and café-au-lait macules



9 year old man with enlarging gluteal mass and café-au-lait patches

Left lower limb plexiform neurofibroma

Gross Description
  • Associated with grossly enlarged and tortuous nerves
  • Deep tumors are often large
  • Often resembles "bag of worms"
  • Highly vascularized and locally invasive
Gross Images

Images hosted on PathOut servers:

Plexiform, courtesy of Mark R. Wick, M.D.

Micro Description
  • Nodular or diffuse
  • Diffuse cases are also known as elephantiasis neurofibromatosa; characterized by an overgrowth of epidermal and subcutaneous tissue (Dermatol Online J 2009;15:7)
  • Hypocellular with myxoid background; contains Schwann cells, fibroblasts and mast cells
  • Occasional nuclear palisading
  • Rarely is pigmented due to melanocytes (J Am Acad Dermatol 2007;56:862)
  • No biphasic pattern of schwannoma
Micro Images

Images hosted on PathOut servers:

NF1, courtesy of Mark R. Wick, M.D.



Images hosted on other servers:

Tongue lesion - Contributed by Dr. R.F. Chinoy



H&E, S100

Facial swelling

Unknown sites

Positive Stains
  • S100 in scattered cells (unlike strong staining in schwannoma)
  • Perineurial cells are EMA+ in plexiform but not in ordinary neurofibromas