Soft tissue
Extraskeletal bone tumors
Ewing sarcoma / PNET
Author: Vijay Shankar, M.D.
Topic Completed: 1 November 2012
Minor changes: 20 November 2020
Copyright: 2002-2021, PathologyOutlines.com, Inc.
PubMed Search: Extraskeletal Ewing sarcoma / PNET
Table of Contents
Definition / general | Radiology images | Case reports | Clinical images | Gross images | Microscopic (histologic) description | Microscopic (histologic) images | Positive stains | Negative stains | Electron microscopy description | Molecular / cytogenetics description | Differential diagnosisCite this page: Shankar V. Ewing sarcoma / PNET. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/softtissuePNET.html. Accessed January 22nd, 2021.
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
- 29 year old man with neck tumor exhibiting focal squamous differentiation (Am J Surg Pathol 2008;32:1742)
- 35 year old woman with abdominal wall mass (Cancer Imaging 2008;8:156)
- 77 year old woman with inguinal mass (Arch Pathol Lab Med 2001;125:1358)
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 Semir Vranić, M.D., Ph.D.
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
Positive stains
- Glycogen, vimentin, CD99 / O13 / mic2, 100, keratin (20%) (Am J Surg Pathol 2000;24:1657)
Negative stains
- CK7, CK19 (usually, Am J Surg Pathol 2000;24:1174)
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
