Kidney tumor
Benign (usually) adult tumors
Renomedullary interstitial cell tumor

Author: Mandolin Ziadie, M.D. (see Authors page)

Revised: 16 July 2018, last major update March 2012

Copyright: (c) 2003-2018,, Inc.

PubMed Search: Renomedullary interstitial cell tumor

Cite this page: Ziadie, M. S. Renomedullary interstitial cell tumor. website. Accessed September 25th, 2018.
Definition / general
  • Usually an incidental tumor
  • Also called renomedullary interstitial cell tumor or renal hamartoma
  • Multiple medullary fibromas are associated with systemic hypertension
  • Medullary interstitial cells regulate intrarenal blood flow, absorption of water and salt and ultimately blood pressure through secretion of prostaglandins
Clinical features
  • Benign
  • Usually found incidentally during surgery for other lesions or at autopsy (1 per 700 cases, Pol J Pathol 2008;59:21)
Gross description
  • Small (< 1 - 5 cm), well circumscribed, tannish white nodules in the renal medulla / pyramids
Gross images

Images hosted on PathOut server:

Medullary fibroma

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Multiple lesions in medullary pyramids

Microscopic (histologic) description
  • Stellate fibroblast-like cells in a background of loose or dense collagenous tissue with entrapped tubules at periphery
Microscopic (histologic) images

Images hosted on PathOut server:

Small stellate cells, some with vacuolated cytoplasm

lesion among
collecting tubules

Images hosted on other servers:

Fibroblast-like cells in myxoid or collagenous stroma

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