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Kidney tumor - adult malignancies

Adult renal cell carcinoma

Tubulocystic carcinoma

Reviewers: Sean Williamson, M.D. (see Reviewers page)
Revised: 30 June 2012, last major update June 2012
Copyright: (c) 2003-2012, PathologyOutlines.com, Inc.

General
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● Mixture of tubules and micro/macro cysts with low-grade nuclear features
● Also called low-grade collecting duct carcinoma, Bellini duct carcinoma
● Not part of WHO 2004 classification
● Origin: appears to derive from proximal convoluted tubule and distal nephron

Epidemiology
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● Rare; mean age 54 years, 85% male (Am J Surg Pathol 2009;33:384)

Clinical description
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● Often an incidental finding, usually low stage
● Prognosis is usually excellent with recurrences but only rare distant metastases or death from disease

Case reports
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● 56 year old man (Case of the Week #51)

Gross description
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● Up to 17 cm, usually well circumscribed, gray-white and cystic (“bubble wrap” appearance), with a medullary location
● Often surrounded by rim of compressed fibrous tissue
● Minimal hemorrhage, necrosis or invasion of adjacent renal parenchyma

Gross images
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Image 1

Micro description
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● Mixture of closely packed tubules and micro/macro cysts of variable sizes with low grade nuclear features (Urology 1997;50:679)
● Tubules and cysts are lined by single layer of cuboidal or columnar cells with abundant eosinophilic cytoplasm, uniform nuclei with distinct nucleoli; often have hobnail appearance
● Overall low grade nuclear features
● Cysts are closely spaced with variable intervening fibrotic stroma
● 40% coexist with papillary renal cell carcinoma
● Minimal mitotic activity, no atypia, no desmoplasia

Micro images
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Low power:
           

       
Various images


PAS


CK7


CD10


Ki-67

Positive stains
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● Mucin, keratins (AE1-3, Cam 5.2 [CK8/18] and CK19, Am J Surg Pathol 2005;29:747)
● Vimentin, EMA, PAX2; variable 34betaE12, variable CK7

Molecular description
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● Distinct molecular signature from other carcinomas
● Often gain of chromosome 7 and 17, loss of Y, suggesting a relationship to papillary RCC (Am J Surg Pathol 2009;33:1840, Am J Surg Pathol 2008;32:177)

Electron microscopy description
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● Short microvilli with brush border organization

Differential diagnosis
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● Multilocular cystic renal cell carcinoma: aggregates of clear cells with atypia within the septae dividing cystic spaces
● Multilocular renal cyst/cystic nephroma: children under 2 years old and women 40-69 years, architecture is predominantly cystic, not tubulocystic; multilocular cysts are lined by flattened or attenuated epithelium with indistinct nucleoli; occasionally hobnail morphology; hyalinized, fibrotic or ovarian-like stroma
● Mucinous tubular and spindle cell neoplasm: predominantly females, typically long tubular profiles or cordlike growth pattern of uniform, low cuboidal cells with eosinophilic, focally vacuolated cytoplasm and spindling; stroma is myxoid and bubbly with abundant extracellular mucin

End of Kidney tumor - adult malignancies > Adult renal cell carcinoma > Tubulocystic carcinoma

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