Kidney tumor - Synovial sarcoma of kidney

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Kidney tumor - adult malignancies

Other adult malignancies

Synovial sarcoma of kidney

Reviewers: Sean Williamson, M.D. (see Reviewers page)
Revised: 12 July 2012, last major update July 2012
Copyright: (c) 2003-2012, PathologyOutlines.com, Inc.

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

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

Case reports
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● 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)

Radiologic images
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CT scan

Gross description
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● 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

Micro description
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● Usually short, intersecting fascicles of monophasic spindle cells with indistinct cell borders, ovoid nuclei and indistinct nucleoli that infiltrate around non-neoplastic, 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

Micro images
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Various images

Hemangiopericytoma-like vascular pattern

Clear cell change and plump spindled cells

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


Case of the Week

Site unspecified


Pleural tumor

Cytology description
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● 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
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● 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
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● Keratin (usually), S100, CD34, smooth muscle actin, desmin

Molecular description
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● SYT-SSX2 transcript due to t(X;18)(p11.2;q11.2) in >90% of cases

Molecular images
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FISH and karyotype (site unspecified)

Differential diagnosis
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● 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 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

End of Kidney tumor - adult malignancies > Synovial sarcoma of kidney

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