Association of silver granules with elastic fibers in amalgam tatoo of the oral mucosa

Objective. Discoloration of the oral mucosa due to amalgam may appear histologically merely as brown pigmentation of the fibrous extracellular matrix. It was the aim of these investigations to identify the fibrous component that contains silver granules. Methods. Biopsy specimens from seven patients with clinically diagnosed amalgam tattoos were investigated by light and electron microscopy as well as by X-ray microanalysis. Results. Light microscopy revealed small brown discolored fibers in all specimens; in sections stained with Weigert's resorcin-fuchsin,they appeared dark violet. Scanning electron microscopy revealed metallic granules associated with thin fibers; by X-ray microanalysis, they exhibited preferentially peaks for silver and sulfur. Transmission electron microscopy detected only electron-dense particles in elastic fibers. Conclusions. With the different morphological methods, silver granules of amalgam tattoos were exclusively detected within elastic fibers. This result indicates that granular brown discoloration of the matrix fibrils is due to silver impregnation of elastic fibers. Therefore, the histopathological diagnosis of amalgam tattoo is possible even in the absence of larger amalgam particles with black appearance.