Retinoids Health Dictionary

This chronic, relapsing in?ammatory skin disease is extremely common, affecting about 2 per cent of the UK population. Frequently it is mild and trivial, affecting only the points of the elbows or knees and the scalp, but in a substantial minority of sufferers the disease is much more widespread and causes considerable discomfort and social embarrassment. Rarely, it can be universal and even life-threatening.

The predisposition to psoriasis is genetic, multiple genes being involved, but postnatal factors such as acute infection, hormonal disturbance, pregnancy and drugs can in?uence or provoke it. The sexes are equally affected and onset is most common in the second or third decade of life.

The psoriatic lesion is dull red, scaly and well de?ned. Scale is shed constantly, either in tiny pieces or as large plaques. The scalp is usually affected but the disease does not cause signi?cant hair loss. The ?ngernails may be pitted or ridged and the toenails grossly thickened. Several clinical patterns occur: in guttate psoriasis, a sudden explosion of multiple tiny lesions may follow a streptococcal throat infection, especially in children. Larger lesions are characteristic of discoid (plaque) psoriasis, the usual adult form. In the elderly the plaques may be mainly in the large body folds – ?exural psoriasis. Rarely, psoriasis may be universal (psoriatic erythroderma), or a sterile pustular eruption may supervene (pustular psoriasis).

Mucous membranes in the mouth and elsewhere are not affected. Psoriasis does not affect internal organs, but in about 1 per cent of subjects an in?ammatory joint disease (psoriatic arthritis) may be associated with the condition.

Treatment There is no absolute cure, but several agents used topically are of value including coal-tar extracts, DITHRANOL, CORTICOSTEROIDS and synthetic derivatives of vitamins A and D. Ultraviolet B phototherapy (and natural sunlight) bene?ts most but not all psoriatics. Systemic therapy, including PHOTOCHEMOTHERAPY, is reserved for severe forms of psoriasis. METHOTREXATE, CICLOSPORIN A and oral RETINOIDS are the most e?ective drugs, but they are potentially dangerous and require expert monitoring.

Patient information may be obtained through the Psoriasis Association.... psoriasis

A disorder in which the skin is permanently dry and scaly. It is usually genetically determined and several di?erent forms are recognised:

Ichthyosis vulgaris Common and inherited as a dominant trait. Beginning in early childhood, it is often associated with atopic eczema (see DERMATITIS). The limb ?exures and face are spared.

X-linked ichthyosis is much less common, more severe and appears earlier than ichthyosis vulgaris. The ?sh-like scales are larger and darker and do not spare the ?exures and face.

Ichthyosiform erythroderma Of two types and very rare: in the recessive form, the appearance at birth is of the so-called ‘collodion baby’; in the dominant form the baby is born with universally red, moist and eroded skin with an unpleasant smell. Gradually, over several months, thick scales replace the ERYTHEMA.

Treatment Minor forms are helped by constant use of EMOLLIENTS and moisturising applications. Cream containing UREA can be valuable. The rare erythrodermic patterns in the neonate require skilled intensive care as thermoregulation is disturbed and massive ?uid loss occurs through the skin. Later in childhood, oral RETINOIDS are useful.... ichthyosis

A RETINOIDS preparation recently introduced for the topical treatment of PSORIASIS. It is

applied in the evening and continued for up to six weeks. Tazarotene is not suitable for those aged under 18.... tazarotene

n. any one of a group of drugs derived from vitamin A. They bind to one or more of six specific receptors that are found on many cells. On the skin they act to cause drying and peeling and a reduction in oil (sebum) production. These effects can be useful in the treatment of severe *acne, *psoriasis, *ichthyosis, and other skin disorders. Retinoids include *isotretinoin, *tretinoin, acitretin, tazarotene, and alitretinoin, which is particularly effective for hyperkeratotic hand eczema. Possible side-effects, which may be serious, include severe fetal abnormalities (if taken by pregnant women), toxic effects on babies (if taken by breastfeeding mothers), liver and kidney damage, excessive drying, redness and itching of the skin, and muscle pain and stiffness.... retinoid