Kidney tumor - cysts, children, adult benign

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Kidney tumor - cysts, children, adult benign

Benign (usually) adult tumors

Medullary fibroma

Reviewers: Mandolin Ziadie, M.D. (see Reviewers page)
Revised: 28 March 2012, last major update March 2012
Copyright: (c) 2003-2012, PathologyOutlines.com, Inc.

General
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● Usually an incidental tumor
● Also called renomedullary interstitial cell tumor or renal hamartoma
● Multiple medullary fibromas are associated with systemic hypertension

Pathophysiology
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● Medullary interstitial cells regulate intrarenal blood flow, absorption of water and salt and ultimately blood pressure through secretion of prostaglandins

Clinical features
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● Benign
● Usually found incidentally during surgery for other lesions or at autopsy (1 per 700 cases, Pol J Pathol 2008;59:21)

Gross description
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● Small (< 1-5 cm), well-circumscribed, tan-white nodules in the renal medulla / pyramids

Gross images
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Multiple lesions in medullary pyramids

Micro description
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● Stellate fibroblast-like cells in a background of loose or dense collagenous tissue with entrapped tubules at periphery

Micro images
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Fibroblast-like cells in myxoid or collagenous stroma

Circumscribed fibrogenic lesion among collecting tubules

Small stellate cells, some with vacuolated cytoplasm

Various images

Positive stains
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● Oil Red O, Sudan Black B

Negative stains
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● CD34

Electron microscopy description
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● Resembles renomedullary interstitial cell of kidney with large cytoplasmic lipid droplets (Hum Pathol 1972;3:559)

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

Ref Updated: 3/9/12

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