Phosphaturic mesenchymal tumors (PMTs) are rare bone and soft tissue tumors that cause tumor-induced osteomalacia (TIO). These tumors are histologically benign and are often associated with excessive expression of fibroblast growth factor 23 (FGF23), leading to chronic hypophosphatemia and bone hypomineralization. The tumor typically presents in middle age with symptoms of chronic bone pain, pathological fractures, and progressive muscle weakness. Definitive diagnosis is often delayed because of the nonspecific presenting symptoms, rarity, small, poorly localized primary tumors, and variable histologic appearance.
We report the case of a 31-year-old male patient, a medical staff, with a history of persistent medical treatment for symptoms of musculoskeletal internal medicine and lumbar radiculopathy, with the disease progressing more and more severely. The patient also underwent various biochemical and imaging tests during the treatment process... but due to the lack of specificity, the underlying disease was still not detected. The final diagnosis was based on a test measuring increased serum FGF23 concentration combined with a PET/CT scan with Ga-68 DOTATATE tracer to examine the whole body, identifying a hidden tumor in the left femoral condyle. Complete surgical removal of the tumor resulted in a spectacular recovery in clinical and biochemical test results compared to before surgery, while meeting the patient's desire to preserve knee function.
Because phosphaturic mesenchymal tumors are very rare (according to the medical literature, there are about 450 cases recorded to date), the tumor grows slowly, and is often located in a difficult-to-find location, so it is easy to miss the diagnosis even though this is a condition that can be completely cured. Therefore, we report in detail a typical clinical case of phosphaturic mesenchymal tumors diagnosed late, and at the same time provide a summary of the medical literature on this rare disease to provide more clinical data on PMT, aim to improve understanding and help clinicians easily "recognize" this rare bone tumor related to the field of metabolic and endocrine disorders.