Bone
Other tumors of bone
Phosphaturic mesenchymal tumor

Author: Nat Pernick, M.D. (see Authors page)

Revised: 18 October 2016, last major update June 2005

Copyright: (c) 2003-2016, PathologyOutlines.com, Inc.

PubMed search: phosphaturic mesenchymal [title] tumor

Cite this page: Phosphaturic mesenchymal tumor. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/bonephosphaturicmesenchymal.html. Accessed December 6th, 2016.
Definition / General
  • Extremely rare
  • Median age 53 years, range 9 - 80 years, slight female predominance
  • Causes rickets or osteomalacia by producing a renal phosphaturic substance that reduces tubal phosphate reabsorption, causing low serum phosphate and resulting oncogenic osteomalacia; also low serum 1,25 dihydroxyvitamin D (Pediatr Dev Pathol 2000;3:61)
  • Most cases of tumor associated oncogenic osteomalacia are due to phosphaturic mesenchymal tumor which produces fibroblast growth factor-23 (a protein that inhibits renal tubular epithelial phosphate transport, Am J Surg Pathol 2004;28:1) or dentin matrix protein 1 (Mod Pathol 2004;17:573)
  • Usually benign
Case Reports
Treatment
Gross Description
  • 2 - 14 cm, arises in soft tissue and bone
Micro Description
  • Hypocellular tumor of bland spindled cells with small nuclei, indistinct nucleoli, osteoclast-like giant cells, myxoid change, hemangiopericytoma-like vessels, distinctive “grungy” calcified matrix, fat, microcysts, hemorrhage, incomplete rim of membranous ossification, metaplastic bone
  • Infiltrative
  • No / rare mitotic activity, no atypia
  • Malignant: rare cases with nuclear atypia, 5+ mitotic figures / 10 HPF, high cellularity, resembles MFH
Micro Images
Images hosted on PathOut server:

Giant cells



Case of the Week #63:

Various images

Positive Stains
Differential Diagnosis
Additional References