Electron microscopic X-ray microanalysis of metals deposited in oral mucosa.

A 35-year-old woman exhibited bluish-brown discoloration of her buccal mucosa suggesting malignant melanoma. Histopathological examination revealed that the pigment was not melanin but caused by metal deposits. Electron microscopically, metallic particles were located on the lamina densa of basal laminae at mucosal epithelium, nerve fibers, and blood vessels and on the microfilaments of elastic fibers as well as in macrophages and fibroblasts. Electron microscopic point X-ray microanalysis revealed that these metallic particles were composed of Ag, Se, Fe, Co, Cu, and S. Analysis suggests that these metals were derived from dental amalgam and that the discoloration was caused by amalgam tattoo.