Seborrhoeic dermatitis ; affected the naso labial folds and eyebrows,Blepharitis may occur.There is eczema of the scalp.
Contact dermatitis : shows distinct margins at the level of the collar if it is caused by an air borne allergens or irritant.
Allergic contact dermatitis: due to finger borne allergen presents problems of diagnosis unless the hands are also affected
Photodermatoses : are also sharply demarcated at the collar line,but do not affect the skin under the chin.
Atopic dermatitis : Characteristic is dryness,chiefly of the forehead and eyelids.Atopic eczema may also be found at other sites.
Pitryasis alba : affects only children.