Background: Localized argyria is uncommon and presents clinically as asymptomatic slate gray macules or blue macules resembling blue nevi. Its histopathologic features are usually similar to those of generalized argyria in which silver granules are found most commonly around the eccrine glands, in the walls of blood vessels, and along elastic fibers. Ochre swollen homogenized collagen bundles resembling ochronosis have not been previously described. Objective: The purpose of this study is to report a series of 5 patients with localized argyria with the histologic feature of "pseudo-ochronosis." In one patient, biopsy was performed on 2 distinct lesions. Methods: All patients underwent skin biopsies for light microscopy and darkfield microscopy. In two patients, the biopsy specimens were analyzed with a mass spectrophotometer; scanning electron microscopy and energy-dispersive x-ray analysis were performed. In one patient, the biopsy specimen was decolorized with 1% potassium ferricyanide in 20% sodium thiosulfate. Results: All 5 patients presented with the typical clinical and histologic features of localized argyria, Ochre swollen and homogenized collagen bundles were seen in all cases. In addition, light microscopy in 4 cases revealed an ellipsoid black globule within a zone of collagen degeneration. Conclusion: The histologic features of localized argyria include swollen and homogenized collagen bundles resembling ochronosis, "pseudo-ochronosis," which may be more common than previously recognized.
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