RESUMEN

Introduction: Phosphaturic mesenchymal tumors (PMTs) are rare bone neoplasms with diverse clinical presentations, often posing diagnostic challenges. Case Report: We describe the case of a 37-year-old female schoolteacher with a PMT localized in the distal femur. Diagnostic indicators included hypophosphatemia, hyperphosphaturia, elevated fibroblast growth factor-23 levels, and clinical symptoms of osteomalacia. Surgical management involved tumor resection and limb salvage surgery with a megaprosthesis. The post-operative period was uneventful, leading to a stable discharge. On follow-up, the patient showed no signs of recurrence, regained full ambulation, remained pain-free, and resumed teaching comfortably. Conclusion: This case highlights the importance of considering PMT in patients with unusual clinical symptoms, accompanied by hypophosphatemia, hyperphosphaturia, and osteomalacia, and demonstrates successful surgical management, leading to a favorable outcome.