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Table of Contents
Definition / general | Essential features | Epidemiology | Diagnosis | Case reports | Treatment | Microscopic (histologic) description | Microscopic (histologic) images | Positive stains | Negative stains | Molecular / cytogenetics description | Differential diagnosis | Board review question #1 | Board review answer #1Cite this page: Iczkowski KA. Synovial sarcoma. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/prostatesynovialsarcoma.html. Accessed March 22nd, 2019.
Definition / general
- Primary prostatic synovial sarcoma is a rare presentation of a well studied disease (see Soft tissue topic), and is one of the few primary sarcomas to occur in the prostate (Arch Pathol Lab Med 2017;141:301)
Essential features
- Spindle and oval cells forming interlacing fascicles
- Aggressive growth and metastasis common
Epidemiology
- Age range of 28 to 63 years
Diagnosis
- 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
- 22 year old man with metastatic tumor to liver and lung (World J Surg Oncol 2014;12:194)
- 37 year old man with monophasic tumor (Am J Surg Pathol 1999;23:220)
- 44 and 46 year old men (J Surg Pathol 2008;16:329)
- Three cases, two with documented metastasis (Korean J Urol 2014;55:797)
- Survival is documented in 3 cases (Histopathology 2006;48:321, Urology 2013;82:160)
Treatment
- 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
- CK7, EMA, Bcl2, CD99, E cadherin and vimentin (most cells) (Arch Pathol Lab Med 2017;141:301)
Negative stains
Molecular / cytogenetics description
- Has SYT-SSX gene fusion due to t(X;18)(p11.2;q11.2) (Int J Surg Pathol 2008;16:329)
Differential diagnosis
- Other sarcomas reported in the prostate include, in descending order of incidence:
- Leiomyosarcoma
- Rhabdomyosarcoma
- Prostatic stromal sarcoma
- Malignant peripheral nerve sheath tumor
- Osteosarcoma
- And a few others
- The above battery of immunostains should help establish the diagnosis
Board review question #1
Which of the following stains when positive helps confirm synovial sarcoma:
- CD34
- CD99
- Cytokeratin 20
- Desmin
- Calretinin
Board review answer #1
