1. Aquarium Allergy – An aquarium allergy is rare, and most people with pet allergies are advised to get an aquarium and pet fish to lower the risks of an allergy occurring. In some rare cases though, a skin rash will develop from exposure to fish and water in the aquarium. Treatment includes antihistamines and avoiding any aquariums to prevent a recurrence of the skin rash.
2. Argyria – This rare rash on the skin is caused by high levels of silver exposure, and the resulting rash makes the skin a bluish color. Sunlight will cause gum colored stains to appear as well, mainly on the forehead, nose, and hands. Treatment for this skin rash involves stopping the abnormal exposure to silver, because as long as the exposure remains the skin rashes will continue to appear.
3. Harlequin Itchthyosis – One of the rarest skin conditions is Harlequin Itchthyosis, and this condition is a birth defect and is visible when an affected infant is born. The disorder is caused by an abnormal gene, named ABCA12. Medications and intensive medical care right after birth has increased the survival rate of these infants substantially, but there is no cure and medications are usually needed for life.
4. Pemphigoid Gestitionis – This condition causes skin rashes to appears during the last two trimesters of pregnancy or after you have given birth to a child, and is extremely rare. Blisters and redness appear and the skin becomes very painful. The rash can leave permanent scarring, and there is no known treatment.
5. Solar Urticaria – Solar Urticaria takes a sun allergy up many levels. With this condition any exposure to ultraviolet radiation and possibly even visible forms of light will cause severe hives and welting. These skin rashes occur even on areas that were not exposed. Treatment can include the use of antihistamines and sunscreens, complete avoidance of any UV radiation, or a process known as photohardening where you are exposed to increasing amounts of this radiation to build up a tolerance.
6. Aquagenic Urticaria – With Aquagenic Urticaria hives and welting occur after any water exposure, no matter how small. In some cases the sweat released by the body contains enough water to cause a reaction. This rash is very rare, and treatment involves the use of capsaicin cream which is applied regularly to your skin.
7. Neutrophilic Dermatosis – Also called Sweets Syndrome, Neutrophilic Dermatosis is a disorder that includes skin rashes as one of the main symptoms, and is rare. The skin will have a response to an allergen that is very severe, and plaques may occur anywhere on the skin. Anti-inflammatory drugs and corticosteroids are usually the treatment given for this condition.