A Pilot Study to Evaluate Topical Sodium Thiosulfate Therapy for Calcinosis Cutis (STS-CALC)

Calcinosis cutis refers to a group of disorders characterized by calcium deposition in the skin (1). The disorders are classified according to etiology into the following types: dystrophic, metastatic, iatrogenic, and idiopathic (1,2). Dystrophic calcification occurs in the setting of varicosities, infection, tumors, and connective tissue disorders (1). The connective tissue disorders most commonly associated with calcinosis cutis are systemic sclerosis and dermatomyositis, although it has also been reported in patients with systemic lupus erythematosus, undifferentiated connective tissue disorder, and mixed connective tissue disorder (2). The pathophysiology of calcinosis cutis is not well understood, and there is a broad range of severity seen, from benign localized, small nodules to large, severely debilitating lesions (2). Although many therapies have been investigated for treatment of calcinosis cutis, including calcium channel blockers, colchicine, minocycline, intravenous immunoglobulin, and bisphosphonates, results have been mixed at best (2). Surgical removal is sometimes feasible in the case of a localized lesion, however, recurrence after surgery is common (2).

Recently, several authors have reported cases of dramatic resolution of dystrophic calcinosis cutis lesions with topical sodium thiosulfate preparations (1,3,4). Systemic sodium thiosulfate therapy is commonly used to treat calciphylaxis in patients with renal disorders with very few adverse events (1). A search of the literature to date yields no formal studies that aim to determine whether topical sodium thiosulfate is truly an effective therapy for calcinosis cutis. As a result, patients are often treated with therapies that are unproven or ineffective and their calcinosis cutis eventually leads to significant pain and disability.

Research Question:

Does treatment of dystrophic calcinosis cutis with topical sodium thiosulfate result in diminution of the lesion and associated pain?

Objective:

The objective of this pilot study is to investigate whether topical sodium thiosulfate is an effective therapy for calcinosis cutis. This study will also determine the feasibility of our protocol and provide information to help direct a future full-scale trial.