Phosphaturic mesenchymal tumor, mixed connective tissue type, non‐phosphaturic variant: Report of a case and review of 32 cases from the Japanese published work

Abstract

Phosphaturic mesenchymal tumor, mixed connective tissue type (PMTMCT) is a rare neoplasm that can cause tumor-induced osteomalacia due to overproduction of a phosphaturic hormone, fibroblast growth factor 23 (FGF23). We report here a case of subcutaneous PMTMCT, non-phosphaturic variant, in the sole. We also review 32 Japanese cases of PMTMCT reported in detail. They occurred in 16 men and 15 women (one was unknown), with ages ranging 20-73 years (median, 48). Tumors were found in soft tissue, bone and sinuses in 17, 11 and four, respectively. A history of long-standing osteomalacia was noted in all cases except two non-phosphaturic variant cases. Serum FGF23 level was elevated in 11 of 12 cases examined. In terms of follow-up information, metastases were found in four patients, and two patients died of disease. In conclusion, PMTMCT is histologically a benign lesion; however, there may be rare metastatic and malignant cases. Wider recognition of the histological features of this unique neoplasm would aid its distinction from the large number of mesenchymal tumors for which it may be mistaken and should enable correct diagnosis of tumors with osteomalacia.

Phosphaturic Mesenchymal Tumor Involving the Head and Neck: A Report of Five Cases with FGFR1 Fluorescence In Situ Hybridization Analysis

“…Only one of the tumors in our series was originally diagnosed as PMT, a pattern consistent with previously published studies [1,5,10]. Tumors arising in the head and neck may be more prone to misdiagnosis as these sites are often biopsied and the small amount of material provided may not demonstrate features that distinguish PMT from similar tumors.…”

“…Because PMT is rare, the diagnosis is often not considered by clinicians and pathologists even in patients presenting with osteomalacia. Indeed, most patients ultimately diagnosed with PMT have experienced osteomalacia for years before the tumor is identified [10]. In one of our cases, the young age of the patient and the presence of skeletal deformities at the time of her initial presentation led the clinicians to consider rickets and other diseases related to vitamin D deficiency.…”

“…Half of all PMTs reported in the head and neck have involved the sinonasal tract; other sites include the pharynx, maxilla, mandible, tongue, floor of mouth, and posterior neck. The true incidence of PMT in the head and neck may be higher than reported as tumors in this region are frequently misdiagnosed as a variety of more common entities including glomangiopericytoma, giant cell tumor, or low grade osteosaroma [10].…”

Phosphaturic Mesenchymal Tumor: 2 New Oral Cases and Review of 53 Cases in the Head and Neck

“…There is a roughly equal distribution between hard and soft tissue with perhaps a slight predilection in bone (53 %) [11][12][13]. Clinical presentation is related to anatomic site affected and may include bone pain, multiple bone fractures, gait disturbance, atrophy of proximal muscles, and osteopenia.…”

Ga-68 DOTATOC PET/CT-Guided Biopsy and Cryoablation with Autoradiography of Biopsy Specimen for Treatment of Tumor-Induced Osteomalacia

“…The diagnosis is clinical and biochemical based on high alkaline phosphatase, normal calcium and parathyroid hormone, high FGF-23, normal or low 1, 25 vitamin D, low serum phosphorus with concomitant high fractional excretion of phosphate in the urine. Rare malignant cases are reported [4]. Localization of culprit tumor confirms the diagnosis and is essential for definitive treatment.…”