Topical Sodium Thiosulfate: A Treatment for Calcifications in Hyperphosphatemic Familial Tumoral Calcinosis?

Context: Hyperphosphatemic familial tumoral calcinosis (HFTC) and hyperphosphatemia hyperostosis syndrome (HHS) are rare diseases characterized by hyperphosphatemia and ectopic calcifications or recurrent episodes of diaphysitis. In the setting of metabolic or inflammatory diseases, recent data suggest that systemic administration of sodium thiosulfate (STS) could be effective in the treatment of ectopic calcifications but may also be poorly tolerated (digestive symptoms, metabolic acidosis). Our group developed a topical formulation of STS to treat ectopic calcifications locally, therefore limiting patient exposure to the drug and its adverse effects.