Chemical, microscopic, and ultrastructural characterization of the mineral deposits in tumoral calcinosis.

Overview

The presence of hydroxyapatite has been determined based on ultrastructure, X-ray diffraction, electron diffraction, and chemical analysis, and confirmed by microprobe analysis in multiple deposits surgically excised from four unrelated patients with tumoral calcinosis. The chemical composition of each of the mineralized deposits resembled bone, rather than dermis, in mineral, uronic acid, total lipid, and complexed acidic phospholipid composition. No collagen abnormalities were detected. However, all of these deposits differed from normal bone mineral, being heavily mineralized and containing larger, more perfect hydroxyapatite crystals. Ultrastructurally, the crystals were both extracellular and within mononuclear cells in close proximity to dilated rough endoplasmic reticulum.