Cutaneous calcification

Normally, calcium and phosphate are in a relatively stable equilibrium in extracellular fluids. In ectopic calcifications, precipitation and deposition of solid material occur in connective tissue, and in rare cases with formation of bony structures (heterotopic ossification) too. Mostly, however, no crystalline calcium salts but rather amorphous precipitates of calcium phosphate and calcium carbonate occur. If these precipitates, which may also contain other ions in addition to calcium, are deposited in dermal and subcutaneous connective tissue, the resulting diseases are collectively referred to as cutaneous calcinoses. The classification of calcinoses depends on their pathogenesis: metastatic calcinosis cutis develops in normal tissues with disturbed calcium and/or phosphate metabolism. More frequently, dystrophic calcinosis cutis occurs in damaged or traumatized tissues without underlying metabolic disorder. The entities formerly referred to as idiopathic calcinoses (solitary congenital nodular calcification, calcinosis of the scrotum/vulva and auricular calcinosis) must be classified as dystrophic calcinoses. The term idiopathic calcinosis is therefore not used in this chapter.