A 75-year-old man presented to the dermatology clinic for treatment of multiple actinic keratoses and evaluation of a black discoloration of his right hand and fingers.
For the past 12 to 14 years, the patient peeled apples for pies several times each year. While doing so, he would develop black discoloration on his right hand, which he held his carbon knife and a stainless steel peeler. The discoloration usually faded after several days. Physical examination of his right palm revealed black macular discoloration that followed the skin lines and was pronounced on the palmar aspect of the fingers. His skin was xerotic and rough to palpation.
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The patient was diagnosed with black dermographism, which literally means “black writing on the skin.” Black dermographism is a discoloration of the skin that appears when fine metallic particles, eroded from metal objects by powders or abrasives on the skin, are deposited in the epidermis.
This purely physical phenomenon, unrelated to metal allergy, can be produced not only on normal skin, but also on cadaver skin, on fabric or on paper. The deposition is always black, regardless of the causative metal, because the particles are extremely fine and thus do not reflect any light.1
It has been proposed that certain substances on the skin, such as powders contained in cosmetics and certain lotions, are hard enough to abrade metal and therefore initiate the discoloration. Comparing common powders used in cosmetics and medications with metals in jewelry can help determine if abrasion will occur.
Stainless steel and chrome-plated objects are harder than powders used in cosmetics and medications and thus are not abraded by them and cannot produce black dermographism.
Carbon, the hardest of all the powders and abundant in urban and industrial dust, readily abrades all metals, including chromium and steel. Calamine lotion, which contains zinc and ferric oxide, and certain cosmetic powders and sunscreens that contain zinc oxide and titanium dioxide abrade most metals used in jewelry (nickel, platinum, silver, gold).1,2
Black dermographism has no real treatment and does not rub off easily. The only form of alleviation is repetitive washing with soap and water. To prevent black dermographism, the skin should be cleansed to remove all hard powders and other abrasives before wearing jewelry or coming in contact with other metallic objects. Jewelry and metal objects should also be cleansed before wearing or using.2,3
In this case, black dermographism was diagnosed based on the patient’s skin condition and previous appearance of the discoloration. Although he had not used any abrasives, lotions or powders on his hands before peeling the apples, the patient’s severely xerotic skin acted as the abrasive to initiate the discoloration.
Black dermographism occurring without powder abrasive has been previously reported; Hurley described it in the setting of rough skin,3 and subsequent authors noted that heavily keratinized areas, such as the palms, are more susceptible to black dermographism.4
Frequent washing with soap and water eventually removed our patient’s discoloration.
Gregg Anthony Severs, DO, practices dermatology at Lackawanna Valley Dermatology Associates in Scranton, Pa. Michele S. Maroon, MD, is director of the dermatology residency program and clinical dermatologist at Geisinger Medical Center in Danville, Pa.
1. Fisher AA. Black dermographism: mechanism for formation of black color. Cutis. 1993; 52:17.
2. Fisher AA. Black dermographism. A physical phenomenon. Cutis. 1974;13:187.
3. Hurley HJ. Black dermographism. Arch Dermatol. 1960;81:329.
4. Rapson WS. Skin contact with gold and gold alloys. Contact Dermatitis. 1985;13:56.