Clinical features and treatment of hypophosphatemia and associated complications induced by Phosphaturic mesenchymal tumors: A case series of six patients.

Phosphaturic mesenchymal tumor (PMT) is a rare benign mesenchymal tumor characterized by excessive secretion of fibroblast growth factor 23 (FGF23), leading to phosphate loss and systemic osteomalacia. Despite recent progress in PMT research, no consensus on diagnosis and treatment guidelines has been established. This case series describes the clinical and pathological features of six pathologically confirmed PMT patients treated at the Third Affiliated Hospital of Sun Yat-sen University from 2010 to 2024, aiming to provide new insights for the management of this condition. The patients, consisting of three males and three females with an average age of 44 years and follow-up periods of 0.5 to 4.5 years, presented primarily with muscle pain and lower limb weakness. One patient experienced loose teeth, and two had palpable, painless masses. One case developed hyperphosphatemia, tertiary hyperparathyroidism, and renal impairment after prolonged phosphate supplementation. Tumor localization was achieved using 18F-FDG or 68Ga-DOTATATE Positron Emission Tomography-Computed Tomography(PET/CT) and MRI, followed by complete surgical resection. Pathological examination confirmed PMT, and postoperative recovery was marked by significant symptom relief and normalization of serum phosphate levels. Two patients experienced recurrence within three years but showed no further recurrence following repeat surgery by the last follow-up. The diagnosis of PMT is challenging and may take years, potentially leading to complications due to inadequate treatment. Complete tumor resection remains the primary treatment, generally resulting in a favorable prognosis; however, long-term monitoring is essential to detect potential recurrences and initiate timely interventions.