Adrenal gland and paraganglia
Other adrenal malignancies
Ewing sarcoma / PNET


Topic Completed: 1 May 2016

Revised: 4 January 2019

Copyright: (c) 2002-2019, PathologyOutlines.com, Inc.

PubMed Search: Ewing sarcoma [title] adrenal
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Cite this page: Gellert LL. Ewing sarcoma / PNET. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/adrenalEwings.html. Accessed May 25th, 2019.
Definition / general
  • A small round cell sarcoma showing pathognomonic molecular findings and varying degrees of neuroectodermal differentiation
Essential features
  • Small round cell sarcoma with occasional pseudorosette formation
  • Pathognomonic molecular finding is t(11;22) with EWSR1 translocation
  • Diffuse membranous CD99 staining
  • Always consider neuroblastoma in the differential diagnosis
Epidemiology
  • Adrenal gland is very rarely implicated
Etiology
  • Driven by pathognomonic and etiological EWSR1 - ETS gene fusion
Clinical features
  • Often presents with pain, sometimes with intermittent fever
Prognostic factors
Case reports
Treatment
  • Chemotherapy, followed with surgery or radiation if localized
Gross description
  • Typically tan - grey with destructive borders and invasive margins
  • Necrosis and hemorrhage common
Microscopic (histologic) description
  • Uniform small round cells with round nuclei, fine chromatin and indistinct cytoplasmic membrane
  • Sometimes show neuroectodermal differentiation (cells oriented toward a central space forming pseudorosettes)
  • Focal spindling seen rarely
Microscopic (histologic) images

Images hosted on other servers:

Uniform small round cells with round
nuclei, fine chromatin and indistinct
cytoplasmic membrane

Solid sheets of small, uniform cells
divided incompletely into clusters
by fibrous septa



Contributed by Lan L. Gellert, M.D., Ph.D.

Uniform small round cells with round nuclei, fine chromatin and indistinct cytoplasmic membrane



Other images

Pseudorosette formation

Metastatic Ewing sarcoma
with characteristic
PAS+ cytoplasmic clearing

Diffuse membranous CD99 staining

Cytology description
  • Cellular smears composed of small, monomorphic round cells
  • Fine nuclear chromatin and round nuclei and scanty clear cytoplasm
  • Occasional pseudorosette - like formations
Cytology images

Images hosted on other servers:

Clusters of monomorphic tumor
cells with vacuolated cytoplasm

Positive stains
  • CD99 - diffuse membranous staining
  • FLI1, ERG
  • Up to 30% with focal cytokeratin immunoreactivity
Negative stains
Molecular / cytogenetics description
  • t(11;22)(q24;q12) EWS-FLI1 gene fusion in 85% cases
  • EWSR1 also fused with other ETS family members (e.g. ERG, ETV)
  • Rarely FUS-ERG or FUS-FEV
Differential diagnosis
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