Electron microscopic study of mineral deposits in idiopathic calcinosis of the scrotum.

An excised specimen from a 39-year-old man with idiopathic calcinosis of the scrotum was examined by electron microscopy. Mineral deposits were located in the dermis in which collagen fibers were numerous. These collagen fibers appeared mineralized to varying degrees. Mineral crystals frequently were present in the cytoplasm of fibroblasts near large deposits. The mineral portion was identified as a compound consisting of calcium and phosphorus, and the elementary mapping of calcium and phosphorus in the skin tissue was analyzed by an energy dispersive x-ray spectrometer. No calcification was observed in dartos muscle cells or in mast cells.