Prostate gland & seminal vesicles
Other malignancies
Synovial sarcoma

Topic Completed: 1 March 2017

Minor changes: 28 February 2019

Copyright: 2003-2019,, Inc.

PubMed search: prostatic synovial sarcoma

Kenneth A. Iczkowski, M.D.
Page views in 2019: 297
Page views in 2020 to date: 128
Cite this page: Iczkowski KA. Synovial sarcoma. website. Accessed August 14th, 2020.
Definition / general
Essential features
  • Spindle and oval cells forming interlacing fascicles
  • Aggressive growth and metastasis common
  • Age range of 28 to 63 years
  • Reportedly established on a core needle biopsy in 1 case and transurethral resection of the prostate in a second; in 8 other cases, on resection
Case reports
  • Combinations of surgical resection, chemotherapy or radiation therapy
  • Surgical procedures range from radical prostatectomy to pelvic extenteration with en bloc penectomy and pubectomy
Microscopic (histologic) description
  • Uniform spindle and oval cells forming interlacing fascicles resembling fibrosarcoma
  • Focally the compact fascicles of tumor cells alternate with hypocellular myxoid tissue resembling peripheral nerve sheath tumors
  • Focal pericytomatous pattern of polygonal cells arranged around dilated, thin walled blood vessels
Microscopic (histologic) images

Contributed by Kenneth Iczkowski, M.D.

A cellular pattern of overlapping uniform spindle
and oval cells forming interlacing fascicles is
evident in this needle biopsy. Pericytomatous
cell arrangement was not prominent

Positive stains
Molecular / cytogenetics description
Differential diagnosis
Board review style question #1
Which of the following stains when positive helps confirm synovial sarcoma:

  1. CD34
  2. CD99
  3. Cytokeratin 20
  4. Desmin
  5. Calretinin
Board review answer #1
B. CD99

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