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Kidney tumor - cysts, children, adult benign

Benign (usually) adult tumors

Papillary adenoma


Reviewers: Mandolin Ziadie, M.D. (see Reviewers page)
Revised: 26 March 2012, last major update March 2012
Copyright: (c) 2003-2012, PathologyOutlines.com, Inc.

General
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● Low-grade (usually) neoplasm also known as renal cortical adenoma

Epidemiology
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● Commonly found at autopsy: 10% at age 21-40 years, 40% at age 70-90
● Increasing numbers during life are being detected with more widespread whole body imaging

Clinical features
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● Associated with chronic pyelonephritis, renal vascular disease, von Hippel-Lindau syndrome, long term hemodialysis and acquired cystic disease (in 1/3)
● Multiple adenomas associated with papillary renal cell carcinoma (Hum Pathol 2007;38:239)

Classification (WHO 2004)
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Clearly benign: 0.5 cm or less, tubulopapillary architecture
Probably benign: same as “clearly benign” but up to 1 cm
Likely malignant: < 1 cm with solid growth pattern or clear cells
Malignant: 1 cm or more (Adv Urol 2008:974848)

Case reports
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● 44 year old man with incidental lesion (Case of the Week #43)

Gross description
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● Well-circumscribed, unencapsulated pale tumor in subcapsular kidney
● Usually 0.5 cm or smaller

Gross images
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Adenoma is 8 cm, but has benign histology and is non-invasive


1.5 cm subcapsular tumor

Small, well circumscribed cortical mass

Micro description
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● Dense papillary / tubular / tubulopapillary architecture composed of small cuboidal cells with scant amphophilic to basophilic cytoplasm, round / oval nuclei (minimal anaplasia - Fuhrman grade 1/2) with stippled to clumped chromatin and indistinct nucleoli
● Variable nuclear grooves, no / rare mitotic figures
● Psammoma bodies / xanthoma cells may be present
● Classified as type 1 (basophilic) or type 2 (eosinophilic), based on criteria for papillary renal cell carcinoma
● Note: small tumors of clear cells are considered to be small renal cell carcinomas, clear cell type and with malignant potential

Micro images
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Incidental tumor

   

Xanthoma cells in stroma; type 1 (basophilic) tumors


Tubular structures lined by cuboidal cells with small nuclei


Circumscribed but nonencapsulated tumor


Tiny tumor has papillary architecture


Figure A: type 1, fig B: type 2

Molecular description
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● Gains of #7, 17, 16, 12 and 20 and loss of Y occur early in papillary renal cell neoplasia (Mod Pathol 2003;16:1053)

Molecular images
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Figure A-single Y present in normal tubules; fig B-gain of #12 (3 signals) in papillary adenoma

Additional references
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Stanford University

End of Kidney tumor - cysts, children, adult benign > Benign (usually) adult tumors > Papillary adenoma

Ref Updated: 3/7/12


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