Soft tissue
Peripheral nerve
Plexiform neurofibroma

Author: Vijay Shankar, M.D.

Revised: 12 September 2018, last major update November 2012

Copyright: (c) 2002-2018, PathologyOutlines.com, Inc.

PubMed Search: Plexiform neurofibroma [title]

Cite this page: Shankar, V. Plexiform neurofibroma. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/softtissueneurofibromaplexiform.html. Accessed November 14th, 2018.
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)
Radiology images

Images hosted on other servers:

Heterogeneous mass of the left submandibular gland

Mass with diffuse heterogeneous enhancement

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 server:

Contributed by Mark R. Wick, M.D.

NF1 patient



Images hosted on other servers:

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

Cutaneous neurofibroma various locations

Large mass on back - pre and postop


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



19 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 server:

Contributed by Mark R. Wick, M.D.

Plexiform

Microscopic (histologic) 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
Microscopic (histologic) images

Images hosted on PathOut server:

Contributed by Mark R. Wick, M.D.

NF1



Images hosted on other servers:

H&E, S100

Facial swelling

Unknown sites



Contributed by Dr. R.F. Chinoy

Tongue lesion

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