Endocrine Abstracts

Hyperphosphatemic familial tumoral calcinosis (HFTC) is a condition characterized by an increase in the levels of phosphate in the blood (hyperphosphatemia) and abnormal deposits of phosphate and calcium (calcinosis) in in the soft tissue in the periarticular location outside the joint capsule.

Case report: This girl presented at the age of 10 years with swelling and pain in the right hip region. On examination a 10×10 cm hard, non-tender swelling with well-defined margin was felt in upper lateral part of her left thigh. Imaging the right hip revealed irregular calcified mass around the right hip mainly along the lateral aspect extending up to the upper part of the metaphysis arising mainly from the gluteus maximus extending laterally to the subcutaneous fat. Tc-99 MDP bone scintigraphy demonstrated abnormal uptake in the right gluteal soft tissue region. Investigations showed high phosphorus, normal calcium, Alkaline phosphatase (ALP), and PTH, low 25(OH) cholecalciferol. Renal function was normal. The calcified mass was totally excised and histopathology and mutations in the FGF23 gene proved the diagnosis of HFTC. Because of elevated serum phosphate she was started on phosphate binder (sevalamer 800 mg five times daily) and nasal calcitonin twice daily in addition to dietary phosphate restriction. On this treatment for 7 years, serum phosphate ranged between 1.78 and 2.1 mmol/l with normal serum calcium and ALP concentrations. Clinical and MRI follow-up showed no evidence of recurrence and no renal or eye abnormalities nor hyperostosis for these 7 years. Linear growth was normal, (Ht SDS =1.8, BMI =16.5). She had normal pubertal development and menstruation.

Discussion: The FGF23 gene provides instructions for making a protein called fibroblast growth factor 23, which is produced in bone cells and signals the kidneys to stop reabsorbing phosphate. Surgical removal should be complete because if a part of it is left, there is inevitable recurrence. Our case proved the efficacy and safety of phosphorus binder and calcitonin as adjuvant therapy to surgery for 7 years.

Conclusion: After removal of the calcified mass, long-term treatment of a patient with a phosphorus binder (sevalamer) and calcitonin prevented any recurrence.