Synovial sarcoma of kidney

Kidney tumor
Other adult malignancies
Synovial sarcoma of kidney

Author: Sean R. Williamson, M.D.

Revised: 19 April 2018, last major update July 2012

Copyright: (c) 2003-2018, PathologyOutlines.com, Inc.

PubMed Search: "Synovial sarcoma" kidney

Table of Contents

Cite this page: Williamson, S.R. Synovial sarcoma of kidney. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/kidneytumormalignantsynovialsarcoma.html. Accessed April 22nd, 2018.

Definition / general

Often previously diagnosed as embryonal sarcoma of kidney (Am J Surg Pathol 2000;24:1087)

Clinical features

Usually extremities of young adults, rare in kidney (< 50 cases reported)

Radiology images

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CT scan

Case reports

21 year old woman (Urol Ann 2011;3:110)
40 year old woman (Case of the Week #19)
60 year old man (Arch Pathol Lab Med 2005;129:238)

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

CD56, CD99, vimentin
Variable bcl2, calponin and EMA
PAX2 and PAX8 often positive in epithelial cysts of primary renal cases, likely due to entrapment and dilation of renal tubules; however, spindled and epithelial components of biphasic synovial sarcoma in general may have weaker positivity (Am J Surg Pathol 2011;35:1264)

Negative stains

Keratin (usually), S100, CD34, smooth muscle actin, desmin

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