Calcinosis cutis is an idiopathic deposition of calcium phosphate (apatite) in skin and subcutaneous tissues. Two cases of eight months' and 14 years' duration were studied. Analysis of the calcium in sweat of advanced case showed levels greater than 15 times normal. X-ray diffraction studies showed large well-crystallized apatite mineral the size of enamel crystals. Electron micrographs showed crystals to be plate-like structures.
Histochemical techniques showed no dermal acid mucopolysaccharides about early sites of calcification. Electron microscopy showed crystals in tissue that were not demonstrable by light microscopy. Electron micrographs of early tissue deposits of calcium showed apatite crystals lying parallel and tangential to collagen fibrils, but no small crystals were noted in ground substance. Larger crystal aggregates appeared to cut across collagen fibrils and to have areas of electron lucency about them.
It is suggested that collagen fibrils are involved in the laying down of apatite particles. The presence of sharp spicules of apatite lying among moving collagen fibrils results in a possible injury to the tissue.
Cornelius CE, Tenenhouse A, Weber JC. Calcinosis CutisMetabolic, Sweat, Histochemical, X-Ray Diffraction, and Electron Microscopic Study. Arch Dermatol. 1968;98(3):219-229. doi:10.1001/archderm.1968.01610150005001