Argyria

Argyria is a permanent blue grey discolouration of the skin, nails and mucosa caused by deposition of silver. It may be generalised, after ingestion or absorption of silver, or localised, after direct contact.

It is now uncommon. Causes are colloidal silver products taken as health remedies, silver nitrate and silver sulphadiazine used on wounds, occupational exposure (silver mining, jewellery, photography), silver containing dental material and acupuncture needles.

Generalised argyria usually follows months or years of exposure, and the total silver dose needed varies between people. The discolouration does not fade after exposure stops.

Pathophysiology.

Absorbed silver is carried in the blood, reduced to silver sulphide and silver selenide, and deposited in the dermis around eccrine glands, in elastic fibres and around small vessels. Sunlight reduces the silver salts to metallic silver and stimulates melanin production, so the colour is darkest on exposed skin.

• Slate grey or blue grey skin, strongest on the face, neck, hands and other sun exposed sites. Nails and gums may be grey.
• Localised argyria shows as small blue grey macules at the site of contact (for example around a wound or acupuncture needle).
• Rare systemic effects with high exposure: silver deposits in kidney, liver, eye and brain.

Red flags.

• Neurological symptoms, visual change or kidney or liver abnormality in a patient with heavy exposure.

• Clinical diagnosis from history of silver exposure and the pattern of discolouration.
• Skin biopsy shows black brown granules in the basement membrane of eccrine glands and around collagen and elastic fibres, which are visible under dark field microscopy. Energy dispersive X-ray analysis confirms silver.
• Blood and urine silver levels can confirm exposure.

Differential diagnosis.

• Cyanosis, methaemoglobinaemia and sulfhaemoglobinaemia.
• Drug induced pigmentation (minocycline, amiodarone, chlorpromazine) and ochronosis.
• Haemochromatosis, Addison disease and heavy metal poisoning (mercury, gold).

• Stop all silver exposure and advise against colloidal silver and silver containing remedies.
• Strict sun protection (broad spectrum SPF 30 or more, hats and clothing), which prevents further darkening.
• Q-switched lasers (alexandrite 755 nm or neodymium doped yttrium aluminium garnet 1064 nm) have lightened pigment in several patients. Test first and warn about variable results, with 3 to 6 treatments at 6 to 8 week intervals.
• Chelation and topical lightening agents are not effective. Camouflage cosmetics.
• Counsel about the permanent nature of the change and psychological effects.

Monitoring. Review every 6 to 12 months, and check kidney and liver function after high exposure.

Referral and escalation. Dermatology; occupational health for work related exposure.