Abstract
Phosphaturic Mesenchymal Tumour (PMT) is a rare and underdiagnosed tumour that causes Tumour-Induced Osteomalacia (TIO). These tumours produce Fibroblast Growth Factor-23 (FGF23), which inhibits renal tubular phosphate reabsorption, leading to hyperphosphaturia and oncogenic osteomalacia. The association of primary Hyperparathyroidism (pHPT) with PMT is extremely rare, with only two cases reported in the literature to date. A 51-year-old male presented in a bedridden state with multiple episodes of fractures throughout his skeleton over six years. Investigations revealed mild hypocalcaemia, marked hypophosphatemia, elevated serum Alkaline Phosphatase (ALP), low 25-Hydroxy Vitamin D, and persistently raised Parathormone (PTH) levels. A 68-Ga-DOTANOC 3D PET (Positron Emission Tomography) scan revealed a 4.1×3.2×2.5 cm DOTA avid mass in the right thigh. FGF23 levels were found to be 1466 pg/mL. A diagnosis of hypophosphatemic osteomalacia with pHPT was made, and the mass was subsequently excised. The thigh mass measured 3.5×2.5 cm and had a tan-brown cut surface. Microscopy revealed a benign spindle cell tumour with a vasoformative pattern and areas of grungy calcification. Immunohistochemistry demonstrated strong positivity for Vimentin, while CD34, CD68, CK, and Desmin were negative. A diagnosis of PMT, Mixed Connective Tissue type, was established. Normal phosphate, calcium, and FGF23 levels were restored after surgery, and the patient was able to walk again. This unusual case of a patient with pHPT and PMT, and the possible existence of a “pHPT-PMT syndrome, “was reported in the Times of India on November 20, 2022, as “Rare phosphorus-guzzling tumour left Dongri man bedridden for three years.” The exact aetiology for the association of PMT and pHPT is not known, and the hypothesis of aberrant gene expression has been implicated.
Published Version
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