Soft tissue
Fibroblastic / myofibroblastic tumors
Proliferative fasciitis

Author: Meggen Walsh, M.D. (see Authors page)
Editor: Jerad M. Gardner, M.D.

Revised: 12 September 2016, last major update June 2013

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

PubMed Search: Proliferative fasciitis [title]

Cite this page: Proliferative fasciitis. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/softtissueproliferativefasciitis.html. Accessed December 7th, 2016.
Definition / General
  • Subcutaneous or fascial proliferation similar to nodular fasciitis, but with large basophilic cells resembling ganglion cells (Cancer 1975;36:1450, Stanford University)
  • Histologically the same as proliferative myositis, but not located in muscle
Clinical Features
  • Usually adults (mean age 50 years)
  • Forearm is most common location (2/3 located in the forearm), also trunk or proximal extremities
  • Rare in patients under 15 years old (but see childhood variant below
  • Rapid growth but benign behavior
Case Reports
Treatment
  • Local excision
Gross Description
  • Usually 3 cm or less, poorly circumscribed subcutaneous mass that may extend horizontally along fascia

Childhood variant:
Micro Description
  • Resembles nodular fasciitis due to zonation effect, tissue culture type growth and plump fibroblastic and myofibroblastic spindle cells, but has large ganglion-like cells with abundant amphophilic to basophilic cytoplasm, round vesicular nuclei (occasionally 2 - 3 nuclei) and prominent nucleoli
  • Ill defined margins
  • Stroma is collagenous or myxoid, often with focal myxoid cystic degeneration
  • Often arborizing vascular pattern
  • Variable mitotic figures but no atypical ones

Childhood variant:
  • More cellular than adult form with prominent ganglion-like cells and pleomorphism resembling rhabdomyoblasts
  • May have many mitotic figures
  • May have acute inflammatory cells and focal necrosis (unusual in adult form)
  • Often no / minimal fibroblasts
  • Pushing border instead of infiltrative like adult form
Micro Images

Images hosted on PathOut servers:
Images from AFIP:

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5


Fig 1: Prominent hemorrhage and vague centering of cellular proliferation on interlobar septa of subcutaneous fat
Fig 2: Mixture of ganglion-like cells, myofibroblasts and inflammatory cells
Fig 3: Ganglion-like cells have abundant amphophilic cytoplasm and prominent nucleoli
Fig 4: Ganglion-like cells mixed with inflammatory cells within myxohyaline matrix
Fig 5: Condensed around thin walled vascular channel

Courtesy of Mark R. Wick, M.D.



Images hosted on other servers:

Myofibroblasts and fibroblasts

Ganglion-like cells

van Gieson stain

Alcian blue-PAS



Childhood variant:

Ganglion-like cells

Ganglion-like cells with infiltrate

Lobulated growth pattern

Cytology Description
  • Cellular smear with spindle cells and large cells with abundant cytoplasm, one to two eccentric nuclei and macronucleoli (Acta Cytol 1985;29:882)
Positive Stains
Negative Stains
Differential Diagnosis
  • Ganglioneuroma: background spindle cell proliferation similar to neurofibroma, ganglion cells and spindle cells are positive for neural markers such as S100
  • Nodular fasciitis: no or very few ganglion-like cells
  • Proliferative myositis: histologically identical, but intramuscular location
  • Rhabdomyosarcoma: background spindle cells appear malignant rather than fasciitis-like; rhabdomyoblasts may have striations; desmin+, myogenin+
  • Sarcoma: large mass, nuclear atypia and pleomorphism in background spindle cells, atypical mitotic figures, often tumor necrosis

Childhood variant:
  • Rhabdomyosarcoma: rhabdomyoblasts may have cross striations (unlike ganglion-like cells); desmin+, myogenin+