Correspondence

Medical Mystery: Skin Discolorations — The Answer

N Engl J Med 2007; 356:2327-2328May 31, 2007

Article

To the Editor:

The medical mystery in the April 5 issue1 involved a 34-year-old bank employee who presented with black discolorations of the skin (Figure 1AFigure 1Elemental Silver in the Corneal Layer of the Epidermis.) on all her fingers. The discolorations had developed in the evening after work. A skin-biopsy specimen of the black spots revealed brownish deposits of elemental silver in the corneal layer (Figure 1B), with a fluorescent aspect on the dark-field microscopical examination (Figure 1C), which is typical of elemental silver. Infrared spectroscopy and microanalysis with x-rays showed that some of the bills the patient had been counting (Figure 1D) were prepared with a combination of silver nitrate and petroleum jelly, a method often used to find a thief. Silver nitrate diffuses into the epidermis and reacts with chloride from sweat to form silver chloride, which is photochemically reduced by ultraviolet light to form colloidal particles of metallic silver; these appear black and persist in the epidermis. An advantage of this method of trapping thieves is that usually other persons or objects cannot be contaminated, because the reaction of silver nitrate and chloride produces silver chloride so rapidly. The discolorations cannot be removed by washing, but they disappear after 1 to 2 weeks with normal epidermal turnover. The thief in this case was never identified.

Stefan Schanz, M.D.
Gisela Metzler, M.D.
University of Tübingen, D-72076 Tübingen, Germany
stefan.schanz@med.uni-tuebingen.de

1 References

1. 1

   Schanz S, Metzler G. A medical mystery -- skin discolorations in a bank employee. N Engl J Med 2007;356:1455-1455
   Full Text | Web of Science | Medline