Lack of response to intravenous sodium thiosulfate in three cases of extensive connective tissue disease-associated calcinosis cutis

Dystrophic calcinosis cutis is a debilitating condition of calcium salt deposition in the skin often occurring in association with connective tissue disease (CTD). Available treatments for calcinosis cutis are unsatisfactory, but given the recent use of topical and intralesional sodium thiosulfate (STS) to treat calcifying disorders, we sought to describe the use of intravenous (IV) STS for CTD-associated dystrophic calcinosis cutis. We report three patients with long-standing and extensive CTD-associated calcinosis cutis treated with IV STS after having failed multiple prior therapies. All three patients experienced fatigue and nausea with STS infusions, and none of the patients had notable clinical or symptomatic improvement of calcinosis. It remains to be seen whether the administration of IV STS earlier in the onset of calcinosis might be of benefit given that these patients all had long-standing and refractory CTD-associated calcinosis. Given the small number of patients in this series, further investigation into the use of IV STS in calcinosis cutis is warranted.