Kidney tumor - Adult malignancies
Other adult malignancies
Synovial sarcoma of kidney

Author: Sean Williamson, M.D. (see Authors page)

Revised: 9 February 2017, last major update July 2012

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

PubMed Search: "Synovial sarcoma" kidney

Cite this page: Synovial sarcoma of kidney. PathologyOutlines.com website. http://pathologyoutlines.com/topic/kidneytumormalignantsynovialsarcoma.html. Accessed May 28th, 2017.
Definition / general
Clinical features
  • Usually extremities of young adults, rare in kidney (< 50 cases reported)
Radiology images

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CT scan

Case reports
Gross description
  • Large, partially necrotic, soft to rubbery mass; smooth walled cyst in 70%
Gross images

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Beige lobulated tumor with focal necrosis

Upper pole mass

Microscopic (histologic) description
  • Usually short, intersecting fascicles of monophasic spindle cells with indistinct cell borders, ovoid nuclei and indistinct nucleoli that infiltrate around nonneoplastic, dilated renal tubules
  • Often foci with hemangiopericytoma-like vascular pattern; cysts lined by hobnail epithelium
  • Rarely rhabdoid (Am J Surg Pathol 2004;28:634), biphasic (epithelial and spindle cells) or poorly differentiated (sheets of undifferentiated round cells with scant cytoplasm and high grade nuclei)
  • Also large cell epithelioid variant, small cell variant and high grade spindle cell variant
Microscopic (histologic) images

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Case of the Week #19



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Various images

Clear cell change and plump spindled cells

Hemangiopericytoma-like vascular pattern


bcl2+, EMA+ (focal), CD99+, CD34-

Site unspecified

Pleural tumor

Cytology description
  • Malignant biphasic tumor (one case) characterized by minimally atypical tubular epithelium, immature spindle cells and foci of coagulative tumor necrosis (Acta Cytol 2003;47:668)
Positive stains
Negative stains
Molecular / cytogenetics description
  • SYT-SSX2 transcript due to t(X;18)(p11.2;q11.2) in > 90% of cases
Molecular / cytogenetics images

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FISH and karyotype (site unspecified)

Differential diagnosis
  • Ewing's sarcoma / PNET: neuroendocrine features including rosettes, CD56-, different translocation
  • Hemangiopericytoma: minimal cellular pleomorphism, staghorn vascular pattern, no / rare mitotic activity, CD34+, no SYT-SSX2
  • Malignant peripheral nerve sheath tumor: more pleomorphic cells with tapering nuclei, S100+, keratin-, CD99-, no SYT-SSX2
  • Metastatic sarcoma: clinical history of primary, no SYT-SSX2
  • Primary retroperitoneal sarcoma: kidney is not primary location, no SYT-SSX2
  • Sarcomatoid renal cell carcinoma: has primary renal cell carcinoma component, sarcomatoid area is often EMA+, vimentin+, no SYT-SSX2
  • Solitary fibrous tumor: collagen fibers, hemangiopericytoma-like vascular pattern, CD34+, no SYT-SSX2