Subcutaneous Injection of Sodium Thiosulfate for Ectopic Calcifications or Ossifications. A Pilot Study

"M0-M6 (run-in phase): medical care and follow-up as usual~M6-M12 (STS phase):~* Patients with iPPSD2 will be treated with subcutaneous infusion using a portable pump.~* Patients with dermatomyositis or systemic sclerosis will be treated with repeated injections every two weeks.~Patients will receive a maximal total number of 11 STS injections. M12: final visit (V5): clinical evaluation, photograph and CT scan of the treated lesion, pain and quality of life evaluation."