Prostate
Other malignancies
Primitive peripheral neuroectodermal tumor / PNET

Authors: Kenneth Iczkowski, M.D. (see Authors page)

Revised: 14 December 2017, last major update October 2017

Copyright: (c) 2003-2017, PathologyOutlines.com, Inc.

PubMed Search: Prostatic primitive peripheral neuroectodermal tumor

Related Topics: Kidney tumor

Cite this page: Iczkowski, K. Primitive peripheral neuroectodermal tumor / PNET. PathologyOutlines.com website. http://pathologyoutlines.com/topic/prostatepnet.html. Accessed December 17th, 2017.
Definition / general
  • Primarily a tumor of soft tissue and bone
  • Belongs to the Ewing sarcoma family of tumors
  • Neural crest tumor of young people
  • Type of small round blue cell tumor
Essential features
Epidemiology
  • Reported age range of 20 - 49 years
Clinical features
  • All cases reported presented with dysuria and pelvic discomfort or anal distention
Laboratory
Radiology description
  • Large and infiltrative soft tissue mass with an ill defined, necrotic region and heterogeneous enhancement¬†
Prognostic factors
Case reports
Treatment
  • Multimodal treatment includes chemotherapy, with or without surgery
  • Treatment with chemotherapy and radiotherapy without surgery may be successful (J Cancer Res Ther 2015;11:668)
Microscopic (histologic) description
  • Solid nests and sheets of small round cells
Microscopic (histologic) images

Images hosted on PathOut server:

Images contributed by Dr. Kenneth Iczkowski:

Partly necrotic

CD99+

Keratin-

Synaptophysin+



Images hosted on other servers:

Various images

25 year old man

Tumor cells (a) are
positive for (b) CD99
(c) BCL2, (d) and
pancytokeratin

Negative stains
Molecular / cytogenetics description
  • Fluorescence in situ hybridization using EWSR1 (22q12) dual color, break apart probe, showing rearrangement of Ewing sarcoma region on chromosome 22, causing t(11, 22) (q24, q12) in 90% of cases (Indian J Pathol Microbiol 2012;55:569)
  • Variant translocations involving chromosome 22q12, chromosome 21q22 (10% of Ewing sarcoma) and chromosomes 7q22, 17q12 and 2q36 (< 1% of Ewing sarcoma)¬†can occur
  • Polymerase chain reaction and sequencing shows EWS / FLI1 type 2 chimeric transcript which is confirmatory
Differential diagnosis
Board review question #1
Positive stains for prostatic PNET include all except:

  1. BCL2
  2. Broad spectrum cytokeratin
  3. CD99 / MIC2
  4. S100
Board review answer #1
D. S100