Psoriasis

Psoriasis is characterised by the presence of red, raised patches covered by silvery-white scales, which is caused by an abnormally fast cell division rate in the epidermis layer of the skin and is a genetically determined disorder. This condition often leads to increased shedding of hairs in the telogen (resting) phase of the hair cycle and some reduction in hair density.

Acne necrotica millaris

This condition is recognised by pustules along the front hairline typically, although they can also occur elsewhere on the upper body. The pustules may be slightly painful and are often pruritic or itchy. When they involve the scalp the pustules may leave small patches of cicatricial (permanent) scarring as they have a central necrosis, which can destroy the hair follicle. This condition is considered to be of an unknown origin, although stress is often incriminated in precipitating occurrences

Pityriasis amiantacea

Pityriasis amiantacea begins with a swollen, discoloured and weeping scalp, which causes the hairs to stick to each other and to the scalp. Following the first stage, the scalp begins to produce a thick layer of silvery white or dull gray scales that pile up along the hair shafts. Although the patches may often be found next to a hair part, the back of the head is a common site. Rather than spreading to the rest of the scalp, a fine, branny scale appears over the unaffected area.

Pityriasis simplex (dandruff)

Pityriasis simplex is known more commonly as dandruff. It is characterised by the excessive shedding of the scalp's epidermal cells, which leads to visible flaking or scaling. These scales can accumulate on the surface of the scalp in localized patches or more diffusely. The exact cause is uncertain, although the bacteria pityrosporum ovale and increased sebaceous activity have been suggested as factors.

Seborrhoeic eczema

This condition is distinguished by redness and patches of scale on the scalp, usually near the ears and hairline as the oil glands become sensitive to the levels of male hormones or androgens in the system. Individuals have a genetically determined predisposition towards this condition and outbreaks can be triggered by stress at different ages in the sufferer.