Seborrhoeic Eczema
Seborrhoeic Eczema is a chronic inflammatory scalp condition occurring in seborrhoeic areas (areas with more sebaceous glands). It spite of the name it is not necessarily an oily condition. It presents differing signs, varying between mild, itchy scaling and redness of the area, to excessive scaling and crusting formed from dried scale over a red and moist scalp.
The whole of the scalp can be affected, particularly the hair line area and behind the ears.

Seborrhoeic eczema can be very itchy, which leads to the sufferer scratching the area introducing secondary infection.

Seborrhoeic eczema occurs in infancy as cradle cap and is rarely seen throughout childhood. It returns at puberty or later and lasts throughout life. Infantile and adolescent forms are likely to be two distinct conditions.

Irritant Dermatitis (Contact Dermatitis)
Irritant Dermatitis is caused by a substance which can create cell damage when applied for the first time in strong concentrations i.e. bleach, relaxer. This is called the primary irritant. The reaction caused may be inflammatory but it is not an allergic reaction.

Primary irritants that may cause non-allergic reactions include shampoos, hair cosmetics such as conditioners, setting lotions, or perm lotions, para-dyes and relaxers on black hair. Plants and metals can also create similar problems.

Allergic dermatitis
Allergic dermatitis is a reaction to a substance previously used on the skin. The reaction takes place some time later. The allergic reaction creates an intensely irritable reaction, which happens after a substance has been applied to the skin.
A few hours or even days after the application of the substance, the affected skin may become swollen, red and blistered or dry and crusted. Mostly the area in contact with the substance is affected but when the scalp is affected, the reaction can spread to the eyes and face and sometimes there can be swollen lymph nodes and secondary infection. There can be anaphylactic shock with subsequent restriction of the windpipe. Allergic dermatitis causes intense itching and burning.

Psoriasis
Psoriasis often begins on scalp or elbows with circular areas of uniform darker/ redder skin clearly differing in colour from adjacent normal coloured skin.

These areas are covered with dry white, adherent silvery scales, which can sometimes be quite dense. These scales are not easily removed but when they are, then coarse lined skin with bleeding points can be seen underneath them.
Other areas that can be affected are the knees, elbows and shins. The fingernails and toenails can be affected with thimble pitting. Stiff and painful joints can accompany psoriasis.

The condition is triggered by stress, skin damage, illness and bacterial infection. Itching to an adjacent area often denotes an extension of the condition.

Pityriasis Amiantacea
Pityriasis Amiantacea is a condition in which there is excessive scaling of the scalp. Thick silvery or yellowish scales encircle the hair shafts and may bind down tufts of hair onto the scalp.

The scales resemble asbestos giving rise to the term amiantacea – the French word for asbestos is ‘amiante’. It may be complicated by secondary infection. When this happens the skin becomes sticky, oozy and crusted.
 
Although this condition looks unsightly, it responds to trichological treatment extremely well.