Successful treatment of calcinosis cutis of fingertip in the setting of CREST syndrome with topical 20% sodium thiosulfate

Abstract

Calcinosis cutis (CC) is a rare chronic process characterized by deposition of insoluble calcium salts in the skin and subcutaneous tissues. There are 5 subtypes of CC: dystrophic, metastatic, idiopathic, iatrogenic, and calciphylaxis.1 Dystrophic calcinosis is the most common type of CC and is seen in association with autoimmune connective tissue diseases such as systemic sclerosis, dermatomyositis, lupus erythematosus, and lupus panniculitis. CC is thought to occur as a result of chronic local tissue injury and is a common complication of systemic sclerosis especially the limited form (CREST syndrome: calcinosis, Reynaud phenomenon, esophageal dysmotility, sclerodactyly, and telangiectasia), affecting approximately 25% of these patients.2 It usually presents as subcutaneous nodules in fingers or areas of pressure such as elbows, knees, or ischial tuberosities and might be associated with pain, soft tissue swelling, ulcers, or deformities, which may lead to functional limitations. There may be a toothpaste-like material protruding from the skin, predisposing to infection.3 Treatment of CC is difficult and challenging, and there is no consensus on the suggested treatments. Because CC is a rare condition, there is a significant absence of controlled clinical trials on its treatment and, the available data for all suggested therapies are generally reported in case reports or small case series.4 Sodium thiosulfate (STS) is an inorganic salt, which increases calcium solubility and has been reported to be helpful in treating calcinosis.2, 3 Here we report a case of CC of the fingertip in the setting of CREST syndrome that responded to treatment with topical STS 20%.