Soft tissue
Extraskeletal bone tumors
Ewing sarcoma / PNET


Topic Completed: 1 November 2012

Minor changes: 25 September 2020

Copyright: 2002-2020, PathologyOutlines.com, Inc.

PubMed Search: Extraskeletal Ewing sarcoma / PNET

Vijay Shankar, M.D.
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Cite this page: Shankar V. Ewing sarcoma / PNET. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/softtissuePNET.html. Accessed October 29th, 2020.
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
Radiology images

Contributed by Mark R. Wick, M.D.

Chest wall

Case reports
Clinical images

Contributed by Mark R. Wick, M.D.

Hand

Gross images

Contributed by Mark R. Wick, M.D.

Superficial (left) and subcuticular (right)



Contributed by Dr. Semir Vranic

Low grade fibromyxoid sarcoma

Microscopic (histologic) description
  • Small round / oval cells with scanty cytoplasm containing glycogen
  • Peritheliomatous pattern (concentration around blood vessels)
  • Usually more neuroepithelial features than similar bone tumors
Microscopic (histologic) images

Contributed by Mark R. Wick, M.D.

Chest wall

Ewing sarcoma / PNET

PAS

FLI1



Ewing sarcoma / PNET

Subcuticularm

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)
Differential diagnosis
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