RESUMEN
Calcinosis cutis (CC) is defined as the deposition of calcium salts on the skin and subcutaneous tissue. It is associated with different conditions, including some autoimmune diseases, and it can generate significant inflammation, pain, and functional impairment. Different therapies have been tried with limited results. Intralesional sodium thiosulfate seems a promising therapeutic option. We report a patient with diffuse systemic sclerosis who presented with two symmetrical plaques on both axillae, which caused pain and skin retraction. The clinical diagnosis was consistent with CC, which was confirmed by skin biopsy and ultrasound. The patient was treated with a 250 mg/ml solution of sodium thiosulfate injected into the plaques. Complete resolution was achieved after three monthly sessions. The only reported adverse effect was a transient burning sensation during the injections. Given its effectiveness and safety, we believe that intralesional sodium thiosulfate could become a valid first-line option for the treatment of CC.