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Kidney tumor - adult malignancies

Adult renal cell carcinoma

Cystic variants of clear cell renal cell carcinoma

Reviewers: Sean Williamson, M.D. (see Reviewers page)
Revised: 29 June 2012, last major update June 2012
Copyright: (c) 2003-2012, PathologyOutlines.com, Inc.

General
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● Up to 15% are cystic; 4 subtypes below (Urology 1986;28:145)

Multilocular cystic renal cell carcinoma

General
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● Composed of multiple cystic spaces, lined by epithelial cells with clear cytoplasm, small aggregates of clear cells within fibrous septa that do not form a solid/expansile mass
● Also called multilocular cystic clear cell renal cell carcinoma, clear cell renal carcinoma with intrinsic multilocular growth pattern, or multicystic clear cell carcinoma
● Origin: appears to have same origin as classic clear cell carcinoma, despite better prognosis

Epidemiology
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● 4% of all clear cell carcinomas, mean age 46-55 years, 1/2 to 2/3 male (J Cancer Res Clin Oncol 2008;134:433, Mod Pathol 2010;23:931)
● Usually lower stage (pT1N0M0) than other renal cell carcinomas

Treatment
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● Usually cured by resection regardless of stage
● Partial nephrectomy may be appropriate; excellent prognosis with 5 year survival of 100% (Am J Clin Pathol 2006;125:217)

Gross description
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● Mean 4 cm, fibrous pseudocapsule surrounds expansile mass composed of variably sized, non-communicating cysts separated by irregular, thick fibrous septa

Gross images
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Cystic tumor resembles multilocular renal cyst

Micro description
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● Variably sized cysts separated by fibrous / hyalinized septa, cysts lined by tumor cells, usually low grade (Fuhrman 1-2), septa may show calcification or ossification, often contain small aggregates of clear cells (that do not form a significant solid/expansile mass, sometimes resembling histiocytes)

Micro images
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Multilocular cyst lined by thin septa containing tumor cells

   
Cystic spaces are lined by clear cells which form sheet-like aggregates

   
Various images

Positive stains
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● MUC1

Negative stains
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● Vimentin, LeuM1

Molecular description
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● Chromosome 3p deletion is present, similar to typical clear cell renal cell carcinoma (Mod Pathol 2010;23:931)

Differential diagnosis
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● Multilocular renal cyst: cysts have flat to hobnail epithelial lining, no nests of clear cells in septa, ovarian-like stroma may be present (Int Braz J Urol 2006;32:187)
● Clear cell carcinoma with cystic degeneration: cyst wall has irregular thickness, large areas of solid architecture grossly or microscopically apparent that are typical of clear cell carcinoma, vimentin+, LeuM1+, usually MUC1- (APMIS 2004;112:183)
● Clear cell papillary renal cell carcinoma: may have a significant cystic component, but also solid areas, branched papillary architecture, branched ducts/tubules, and “secretory cells” with nuclei aligned away from the basement membrane (similar to secretory endometrium) – CK7+, CA-IX +, CD10 -, AMACR -
● Tubulocystic carcinoma: Fuhrman grade 2-3, cuboidal to hobnail lining cells with eosinophilic cytoplasm

Clear cell renal cell carcinoma with intrinsic unilocular growth pattern

Micro description
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● Thick irregular wall lined by tumor cells

Clear cell renal cell carcinoma with cystic degeneration

General
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● An extensively cystic/necrotic tumor may still exhibit aggressive behavior even if only rare identifiable tumor cells (Am J Surg Pathol 2000;24:988)

Micro description
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● Hemorrhage, necrosis, thick irregular cyst wall, may be papillary/pseudo-papillary, may be few residual tumor cells

Clear cell renal cell carcinoma originating in a benign cyst

Case reports
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● Controversial – cases include multilocular renal cysts with renal cell carcinoma (Chang Gung Med J 2003;26:772, Int Braz J Urol 2006;32:187)

End of Kidney tumor - adult malignancies > Adult renal cell carcinoma > Cystic variants of clear cell renal cell carcinoma

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