<unk>  is a blanket term literally meaning "inflammation of the skin".  It is usually used to refer to eczema, which is also known as<unk>  eczema. 
There are several different types. Usually all of them have in common an allergic reaction to specific allergens.
Dermatitis
Alopecia
Keratitis
Arthralgia
Scalp rash
Photosensitivity
Acne
Mouth sores