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

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

Revised: 30 January 2017, last major update March 2012

Copyright: (c) 2003-2017,, Inc.

PubMed Search: Renomedullary interstitial cell tumor

Cite this page: Renomedullary interstitial cell tumor. website. Accessed March 25th, 2017.
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

Images hosted on other servers:

Multiple lesions in medullary pyramids

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

Various images

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