Subcutaneous calcification of the lower legs in a patient with mixed connective tissue disease

A 56-year-old woman who had been treated for mixed connective tissue disease (MCTD) noticed a skin ulcer on the lower leg. There was no history of trauma. X-rays of the lower legs showed extensive calcification in the soft tissue. Biopsied tissue from the ulcer showed marked calcium deposition with necrosis. Laboratory findings revealed normal serum calcium and phosphate levels and normal parathyroid function. On the basis of these findings, we diagnosed skin ulcer due to subcutaneous dystrophic calcification associated with MCTD. The ulcer was gradually reduced in size and epithelialized by treatment with local debridement and antibiotics.