Calcinosis cutis: part I. Diagnostic pathway.

Calcinosis cutis is characterized by the deposition of insoluble calcium salts in the skin and subcutaneous tissue. The syndrome is separated into five subtypes: dystrophic calcification, metastatic calcification, idiopathic calcification, iatrogenic calcification, and calciphylaxis. Dystrophic calcification appears as a result of local tissue damage with normal calcium and phosphate levels in serum. Metastatic calcification is characterized by an abnormal calcium and/or phosphate metabolism, leading to the precipitation of calcium in cutaneous and subcutaneous tissue. Idiopathic calcification occurs without any underlying tissue damage or metabolic disorder. Skin calcification in iatrogenic calcinosis cutis is a side effect of therapy. Calciphylaxis presents with small vessel calcification mainly affecting blood vessels of the dermis or subcutaneous fat. Disturbances in calcium and phosphate metabolism and hyperparathyroidism can be observed.