Intracranial phosphaturic mesenchymal tumor, mixed connective tissue variant presenting without oncogenic osteomalacia.
BACKGROUND
Phosphaturic mesenchymal tumor, mixed connective tissue variant (PMTMCT) is a rare tumor typically occurring in soft tissues and bone, causing oncogenic (tumor-induced) osteomalacia (TIO) through secretion of the phosphaturic hormone, fibroblast growth factor-23 (FGF-23). Rare tumors identical to PMTMCT occur without known TIO. Intracranial localization of PMTMCT is extremely rare, with only two cases reported in the literature. We present a very unusual case of a patient with an intracranial PMTMCT that presented with neurologic changes without osteomalacia.


METHODS
A 67-year-old woman presented with progressive incontinence, apathy, and abulia after having undergone a total knee replacement 1 month earlier. Imaging disclosed a large left frontal anterior fossa mass. She underwent uncomplicated surgical resection of this tumor. Surprisingly, histopathology suggested PMTMCT. Reverse transcription polymerase chain reaction (RT-PCR) assay demonstrating FGF-23 expression in the tumor confirmed the diagnosis. Serum FGF-23 levels postoperatively were normal and she had no clinical or laboratory evidence of osteomalacia or phosphaturia.


CONCLUSIONS
This report should serve to alert clinicians to the possibility that PMTMCT can be included in the differential diagnosis of intracranial masses even in the absence of tumor-induced osteomalacia.
Department of Neurosurgery, Mayo Clinic College of Medicine, 200, 1  St. SW, Rochester, MN, USA.
Regina S
RS
Bower
Wilson P
WP
Daugherty
Caterina
C
Giannini
Ian F
IF
Parney
Intracranial; neoplasm; neuropathology; oncogenic osteomalacia