Soft tissue
Extraskeletal bone tumors
Extraskeletal Ewing sarcoma / PNET

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

Revised: 10 August 2016, last major update November 2012

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

PubMed Search: Extraskeletal Ewing sarcoma / PNET

Cite this page: Extraskeletal Ewing sarcoma / PNET. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/softtissuePNET.html. Accessed December 9th, 2016.
Definition / General
  • Rare soft tissue tumor, morphologically indistinguishable from Ewing sarcoma of bone, may represent extension of bone tumor into soft tissue
  • Usually age 30 or less, occasionally age 50+, usually male preponderance
  • Often chest wall, lower extremities, paravertebral region; also pelvis, hip region, retroperitoneum, upper extremities (Cancer 2011;117:3027)
  • Aggressive; common metastases to lung, bones
Case Reports
Clinical Images

Images hosted on PathOut servers:

Chest wall (left) and hand (right), courtesy of Mark R. Wick, M.D.

Gross Images

Images hosted on PathOut servers:

Superficial (left) and subcuticular (right), courtesy of Mark R. Wick, M.D.



Images hosted on other servers:

Knee

Micro Description
  • Small round / oval cells with scanty cytoplasm containing glycogen
  • Peritheliomatous pattern (concentration around blood vessels)
  • Usually more neuroepithelial features than similar bone tumors
Micro Images

Images hosted on PathOut servers:
Images courtesy of Mark R. Wick, M.D.:

Chest wall

Ewing sarcoma / PNET

PAS

FLI1



Ewing sarcoma / PNET

Subcuticularm



Images hosted on other servers:

Inguinal mass

Various images

Negative Stains
Electron Microscopy Description
  • Primitive cells, abundant cytoplasmic glycogen, poorly developed cell junctions, no neural features
Molecular / Cytogenetics Description
  • t(11;22)(q24;q12) fusion transcript by RT-PCR of FLI1-EWS genes
  • t(21;22)(q12q12) of ERG-EWS genes
  • t(7;22)(p22;q12) of ETV1-EWS genes
  • t(17;22)(q12;q12) of E1AF-EWS genes
  • t(2;22)(q33;q12) of FEV-EWS genes
  • t(4;22)(q31;q12) (Mod Pathol 2011;24:333)
Molecular / Cytogenetics Images

Images hosted on other servers:

t(4;22)(q31;q12)

Differential Diagnosis