DSS 2010-1DSS 2010-1

Sarah E. Martin, M.D.Eyas M. Hattab, M.D.

Indiana University School of Medicine86th Annual Meeting of the AANP

June 10-13, 2010

Clinical HistoryClinical History

61 yo woman with a history of multiple fractures and hypophosphatemia for 6 yrs

Presented with bilateral weakness and shooting pains in her legs after a fall

MRI: multi-lobulated, vividly enhancing, heterogeneous T12 mass with extension into epidural space and paraspinal musculature

Diagnosis?Diagnosis?

Phosphaturic mesenchymal Phosphaturic mesenchymal tumor, mixed connective tissue tumor, mixed connective tissue

variant (PMTMCT)variant (PMTMCT)

PMTMCTPMTMCT

Definition– Largely benign, morphologically distinct

mesenchymal neoplasm almost invariably associated with oncogenic osteomalacia

Incidence– Extremely rare, ~ 150 cases described in the

literature

Historical perspective– 1987: Weidner and Santa Cruz coined term

– 2004: Folpe et al. fully characterized PMTMCT

PMTMCTPMTMCT Location

– Soft tissues and bones of the extremities

– Only rarely in axial skeleton (index case)

Etiology

– FGF-23 overexpression: inhibits trans-epithelial phosphate transport in renal tubules, resulting in renal phosphate wasting and subsequent osteomalacia

Clinical features:

– 25-77 years; female predominance

– Bone pain, multiple fractures

– Hypophosphatemia, hyperphosphaturia, and osteomalacia; fail vitamin D therapy

– Chronic, protracted history before tumor is discovered

PMTMCT: pathologyPMTMCT: pathology Gross:

– Superficial and deep soft tissues– Well-circumscribed

Microscopic – Low cellularity, bland spindled cells– Myxochondroid/osteoid-like matrix– Dystrophic calcification, incomplete rim of ossification – HPC-like vessels, microcysts, hemorrhage– Osteoclast-like giant cells

Immunohistochemistry – FGF-23

PMTMCT: pathologyPMTMCT: pathology Differential diagnosis:

– Hemangiopericytoma– Giant cell tumor– Osteoblastoma– Osteosarcoma– Mesenchymal chondrosarcoma– Hemangioma

Keys to diagnosis:– Awareness of entity– Clinical history of osteomalacia (not universal)– Morphologic heterogeneity

PMTMCT: managementPMTMCT: management Treatment

– Surgical resection is curative of both tumor and osteomalacia

Prognosis– Generally excellent after complete resection– Rare malignant forms have been reported

Increased mitoses, high nuclear grade and high cellularity

Local recurrence; lung and skeletal metastases reported

The end.The end.