Phosphaturic mesenchymal tumor

Soft tissue
Mesenchymal tumors
Phosphaturic mesenchymal tumor

Author: Vijay Shankar, M.D. (see Authors page)

Revised: 19 September 2016, last major update November 2012

Copyright: (c) 2002-2016, PathologyOutlines.com, Inc.

PubMed Search: Phosphaturic mesenchymal tumor

Table of Contents

Definition / General

Benign tumor of bone or soft tissue associated with rickets and osteomalacia (Am J Surg Pathol 1989;13:588)
Most cases of tumor associated oncogenic osteomalacia are due to phosphaturic mesenchymal tumor, which produces fibroblast growth factor-2, a protein that inhibits renal tubular phosphate reabsorption (Am J Surg Pathol 2004;28:1) or dentin matrix protein 1 (Mod Pathol 2004;17:573)

Epidemiology

Extremely rare, median age 53 years, range 9 - 80 years, slight female predominance

Laboratory

Low serum phosphate, renal phosphate wasting, low 1,25-dihydroxy Vitamin D3

Case Reports

22 year old man with tumor of craniofacial sinuses (Clin Cases Miner Bone Metab 2011;8:45)
42 year old woman with tumor of ethmoid sinus (Indian J Pathol Microbiol 2010;53:384)
42 year old woman with mandible tumor (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2009;108:925)
45 year old man with mixed connective tissue varian (Intern Med 2006;45:1157)

Treatment

Complete excision causes dramatic reversal of signs and symptoms

Clinical Images

Images hosted on other servers:

Tumor of ethmoid sinus

Gross Description

2 - 14 cm, arises in soft tissue and bone

Micro Description

Hypocellular tumor of bland spindle cells with small nuclei, indistinct nucleoli
Has hemangiopericytoma-like vasculature, osteoclast-like giant cells, distinctive "grungy" calcified matrix, fat, microcysts, hemorrhage, incomplete rim of membranous ossification, metaplastic bone
Infiltrative
No / rare mitotic activity, no atypia
Malignant cases: rare cases with nuclear atypia, 5+ mitotic figures / 10 HPF, high cellularity, resembles MFH

Micro Images

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Tumor of craniofacial sinuses

Tumor of ethmoid sinus

Mandible tumor

Positive Stains

Fibroblast growth factor-23, dentin matrix protein 1

Differential Diagnosis