Adrenal gland and paraganglia
Other adrenal malignancies
Ewing sarcoma / PNET

Author: Lan L. Gellert, M.D., Ph.D. (see Authors page)

Revised: 11 May 2016, last major update May 2016

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

PubMed Search: Ewing sarcoma [title] adrenal
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
Micro 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
Micro Images

Images hosted on Pathout server:

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




Images hosted on Flickr - contributed by Dr. Lan L. Gellert:

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



Images hosted on other servers:

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