Metal dermatitis: An allergic skin reaction often caused by nickel, chromate and mercury. Usually pure metals do not cause allergic reactions, except for nickel, and only when compounds of metals cause allergic reactions.
I. What are the types of metal dermatitis?
1, black skin scratching disease (back dermatographism): gold, silver, titanium and other metal powders on the skin caused by friction metal particles deposited.
2, nickel dermatitis (nikel dermatitis): nickel caused by ACD than other metal compounds are more, more common in women.
3, chromium dermatitis (chromium dermatitis): chromate as the primary irritant and allergic substances cause skin ACD. polymorphic, mild follicular dermatitis, cone-shaped non-through ulcers (chromium cavity).
4, mercury dermatitis (mercury dermatitis): mercury preparations can act not only as irritants, but also as sensitizers, dermatitis can be caused by topical or internal mercury preparations. Mercury chloride (1:1000), phenyl mercury salts (herbicides, insecticides, anti-mold agents, fillers, etc.), mercury nitrate (etching, relief), thimerosal, amalgam, etc.
5, cobalt dermatitis (cobalt dermatitis): cobalt is often mixed with nickel as a contaminant, they have similar characteristics. But do not produce cross-reactivity.
6, arsenic dermatitis (arsenical dermatitis): one of the most common dermatitis, often appearing folliculitis, with secondary pyoderma, boils, ulcers on the extremities.
7, other metal dermatitis: rare. Gold dermatitis is caused by gold jewelry, especially gold rings with contamination of radon and its decay products. Gold tooth is a kind of gold salt with allergenic properties. Patients who stop wearing all gold jewelry will have their dermatitis symptoms disappear. Platinum dermatitis is similar to nickel dermatitis. Zinc, aluminum, copper sulfate, titanium and antimony dermatitis are rare.
8, systemic contact dermatitis: metallic nickel, chromium, cobalt compounds, cobalt-chromium alloy dental brackets, toothpaste in aluminum oxide, etc.
Second, the pathogenesis of metal dermatitis?
Recent studies have demonstrated that not only CD4+ T cells but also other phenotypes of effector T or B cells are involved in the inflammatory response in nickel ACD. Chemokines can mediate the chemotaxis and homing of skin lymphocytes by binding to their corresponding receptors, regulating the migration and localization of T cells, B cells and dendritic cells to specific sites in lymphoid tissue.
What is the association between contact dermatitis and patch test?
Nickel metal and potassium dichromate are common allergens, and the presence of other allergens can cause false positive reactions to other allergens.
However, national and international patch test studies have shown that contact dermatitis can be diagnosed by patch test in about 30% of patients with eczema dermatitis. The most common allergens are nickel sulfate (14.0%), aromatic mixture (12.7%), p-phenylenediamine (8.7%), and cobalt chloride (7.3%). In a recent summary of the analysis of patch test results and changes in antigen positivity in 906 cases of dermatitis eczema-like skin diseases in Beijing, it was found that the positivity rate of nickel sulfate increased significantly from 15.3% in the previous three years to 23.5%. The total positive patch test rate for hand eczema was 46.7%, and 55.1% of the papular hand eczema, which accounted for 65.7% of the total, was positive, indicating that contact metaplasia may play a role in the pathogenesis of most papular hand eczema, and that patch tests must be performed on all chronic hand eczema to search for possible causes.
Contact dermatitis in children was once thought to be uncommon, but in recent years an increasing trend has been reported, possibly due to the increase in ear piercing causing nickel sensitivity.
IV. What are the new developments in the diagnosis of contact dermatitis?
Dermatitis diagnosis is currently being studied abroad with different gene transcripts as diagnostic markers for ACD. Patients with chromium metal-induced ACD were selected as controls with healthy individuals and patients with nickel allergic dermatitis to study the differences in gene transcription in peripheral blood mononuclear cells, and it was found that there were significant changes in 26 genes in chromium ACD patients compared with normal controls, among which the genes with specific diagnosis were two upregulated genes, ETS2 and CISH, and one downregulated gene, CASP8; nickel allergic dermatitis with chromium allergic dermatitis have the same genetic alterations. The polymorphism of the TNF-α gene-308 locus is associated with individual susceptibility to ICD, and this finding provides a nonspecific genetic marker for screening susceptible individuals for irritant contact dermatitis.
V. What is the main diagnostic basis for nickel dermatitis?
1. History of exposure to nickel-containing substances.
2. Matching skin lesions at the contact site.
3. Positive nickel sulfate patch test.
What are the principles of treatment for nickel dermatitis?
1, clear diagnosis, avoid contact.
2, according to the principles of dermatitis eczema treatment.
Seven, how to prevent the occurrence of nickel dermatitis?
In 1993, the U.S. FDA recommended that the allowable nickel dose for nickel-sensitive individuals is 50 μg. Soy products are rich in nickel, so patients are advised to avoid soy products such as soy milk, tofu, soy sauce and vegetable pods. Iron deficiency leads to increased nickel absorption; it is best to cook food without nickel-containing aluminum, stainless steel or glass products. Iron low-nickel foods include beef, pork, chicken, lamb, game fish and animal liver, etc. It is recommended to eat fruits rich in vitamin C such as citrus, strawberries, cabbage, etc.
2, the prevention of irritant contact dermatitis (ICD) mainly take protective measures such as wearing protective gloves, protective clothing, and the use of barrier creams and humidifiers.