1. Allergy of the aquarium – An allergy to the aquarium is rare and most people with allergies to pets are advised to obtain an aquarium and pet fish to reduce allergy risks. In some rare cases, however, a rash will develop from exposure to fish and water in the aquarium. Treatment includes antihistamines and avoiding any aquariums to prevent recurrence of the rash.
2. Argyria – This rare rash is caused by high levels of exposure to silver and the resulting rash makes the skin bluish in color. Sunlight will also cause gum-colored spots to appear, mainly on the forehead, nose and hands. Treatment of this rash involves stopping the abnormal exposure to silver, since as long as the exposure remains the rashes will continue to appear.
3. Ichthyosis of Harlequin – One of the rarest skin conditions is harlequin ichthyosis and this condition is a birth defect and is visible at the birth of an affected child. The disorder is caused by an abnormal gene called ABCA12. Drugs and intensive medical care immediately after birth have substantially increased the survival rate of these children, but there is no cure and drugs are usually necessary for life.
4. Gestition pemphigoid – This condition causes rashes to appear during the last two trimesters of pregnancy or after giving birth to a baby and is extremely rare. Blisters and redness appear and the skin becomes very painful. The rash can leave permanent scars and no treatment is known.
5. Solar urticaria – Solar urticaria brings solar allergy to many levels. In this condition, any exposure to ultraviolet radiation and possibly also to visible forms of light will cause severe hives and luxuriance. These rashes also occur on areas that have not been exposed. Treatment may include the use of antihistamines and sunscreen, complete evasion of any UV radiation or a process known as photo-cure where you are exposed to increasing amounts of this radiation to create a tolerance.
6. Aquagenic urticaria – With Aquagenic Urticaria, urticaria and scarring occur after any exposure to water, no matter how small. In some cases the sweat released by the body contains enough water to provoke a reaction. This rash is very rare and the treatment involves the use of capsaicin cream which is regularly applied to the skin.
7. Neutrophilic dermatosis – Also called sweet syndrome, neutrophilic dermatosis is a disorder that includes rashes as one of the main symptoms and it is rare. The skin will have a response to a very serious allergen and plaques can occur anywhere on the skin. Anti-inflammatory drugs and corticosteroids are generally the treatment administered for this condition.