Other tumors
Primitive neuroectodermal tumor (PNET)

Author: Deepali Jain, M.D. (see Authors page)

Revised: 4 January 2018, last major update August 2012

Copyright: (c) 2002-2018,, Inc.

PubMed Search: Primitive neuroectodermal tumor PNET pancreas

Cite this page: Jain, D. Primitive neuroectodermal tumor (PNET). website. Accessed November 21st, 2018.
Definition / general
  • Small round blue cell tumor with evidence of neuroectodermal differentiation; similar to tumors at other sites
  • See also kidney tumor chapter
  • Mean 18 years (range 6 to 25 years, Am J Surg Pathol 2002;26:1040)
  • Usually soft tissue or bone of children / young adults, rare in pancreas (1% of pancreas sarcomas)
  • At all sites, 5 year survival is 50%
Case reports
Gross description
  • Tumors in head of pancreas, 3.5 to 9.0 cm
Microscopic (histologic) description
  • Sheets and lobules of small round cells with scant cytoplasm
  • Prominent nuclear molding, frequent mitotic activity
  • Often infiltrate into peripancreatic soft tissue
  • Variable tumor necrosis
  • Usually no rosettes
Microscopic (histologic) images

Images hosted on other servers:

Sheets of small
round cells with
rich fibrovascular

Rudimentary rosette

Diffusely CD99+

Site unspecified - left: sheets of uniform, small, round, blue cells; middle: Homer-Wright rosettes; right: atypical PNET with larger cells that often have a prominent nucleolus

Positive stains
Negative stains
Molecular / cytogenetics description
  • t(11;22)(q24;q12)
Differential diagnosis