Facial skin is thinner and more delicate than skin elsewhere and
unlike most other areas has numerous densely packed large hair follicles
and sebaceous glands. It also has a very distensible blood supply
that reaches very near the surface. Two other features of facial
skin set it aside from other areas - it is the area of skin most
exposed to sunlight and airborne allergens and it is very important
in social recognition and communication. All this may explain why
some common rashes look different on the face while other skin disorders
occur on facial skin alone.
Seborrhoeic dermatitis
This is a common distinctive form of eczema now believed to be due
to infection with pityrosporum ovale - a yeast-like micro-organism
that commonly lives on normal skin. Its name is misleading because
it is not due to disease of the sebaceous glands and those with
the condition do not necessarily have a greasy skin. It is best
thought of as a 'constitutional' disorder, being a persistent skin
problem in predisposed individuals. Although there is a type of
dermatitis in infants that is labelled 'seborrhoeic', this is probably
not the same disease. Seborrhoeic dermatitis is essentially an adults'
disease.
Characteristically, diffuse red scaling patches occur in the nasolabial
grooves, in and behind the ears and on the scalp and eyebrows. The
front of the chest and the major body flexures may also be affected.
In the elderly the disorder may spread to affect large areas of
skin and may even become erythrodermic. Seborrhoeic dermatitis tends
to flare at times of stress and lasts for several weeks or months
before subsiding for a variable period.
Atopic dermatitis Facial skin is often involved in atopic dermatitis
and the resulting appearance is characteristic. The skin seems dry
and finely scaling but the front and sides of the neck may show
a rippling or reticular pattern of pigmentation. There is slight
pallor of the facial skin and extra creases below the eyes. This
atopic creasing is probably the result of oedema and thickening
from continual rubbing of the eyes due to irritation.
Allergic contact dermatitis This often picks out the face either
because the sensitizing agent is airborne in the envir onment or
because the allergen has been inadvertently transferred there by
the hands (see Chapter 34). The eyelids and sides of the neck are
the sites that are usually involved.
Perioral dermatitis This is a papular disorder of the face that
is less common now than it used to be - probably because potent
corticosteroids are less used on the face than they once were. This
condition is distinguished by myriads of tiny papules occurring
around the mouth, and responds quickly to oral tetracyline.
Psoriasis This does not often affect facial skin, and when it does
it tends to look and behave like seborrhoeic dermatitis.
