Psoriasis

Synonyms :  

Clinical features, Diagnosis, Management, Prognosis, Nutrition, Herbs,

Psoriasis is a non-infectious, inflammatory disease of the skin, characterised by well-defined erythematous plaques with large, adherent, silvery scales. The main abnormality in psoriasis is increased epidermal proliferation due to excessive division of cells in the basal layers and a shorter cell life cycle. The transit time of skin cells through the epidermis is shortened and the epidermal turnover time falls from 28 to 5 or 6 days. Capillary dilation and increased vascularisation in the dermis always accompany these lesions and are responsible for erythema. 

1-3% of general population has psoriasis, it may start at any age but is often seen between 15 and 40 years. The course of disease is unpredictable but is usually chronic with exacerbations and remissions. 

The cause is unknown but the following factors are involved:

       Genetic. There is frequently a genetic predisposition. A child with one affected parent has a 25% chance of developing the disease and this rises to 60% if both parents are affected. The type of inheritance is unclear but may be polygenic or autosomal dominant with incomplete penetrance.

       Biochemical. It is not known if biochemical abnormalities are the cause or result of increased epidermal proliferation. There are increased levels of prostaglandins, leukotrienes and their precursors. These may cause both the increased cellular proliferation seen in psoriasis and the inflammatory changes in the dermis. There are also various other biochemical abnormalities which may contribute to the disease.

       Immunopathological. Many immunological abnormalities have been found but their role is uncertain. Immune complexes with epidermal antigens have been detected in damaged skin. One theory postulates that chronic irritation may uncover certain dermal antigens which then initiate prolonged immune response. The dermal mononuclear infiltrate is mainly of T lymphocytes, most of which are of the helper type.

       Dermal. There is substantial evidence to suggest that the increased epidermal cell proliferation of psoriasis is related to the increased replication and metabolism of dermal fibroblasts, but the nature of this link is unknown. 

Given the basic defect, an individual may not inevitably develop psoriasis but certain precipitating factors make this more likely. Although there appears to be no obvious precipitating factor in about 70% of exacerbations of psoriasis, the following factors are responsible for the minority of flare-ups:

Trauma, when the erupting lesions appear in areas of skin damage such as scratches or surgical wounds (Koebner’s phenomenon).

Infection, especially streptococcal throat infection.

Sunlight; although UV light is usually therapeutic, 10% of psoriatics become worse.

Drugs such as antimalarials, beta-blockers and lithium (for mania) may worsen psoriasis.

Emotions such as anxiety seem to precipitate some exacerbations.

Clinical features:  < BACK TO TOP >

       Psoriasis occurs in several common patterns, and typically there is no itching.

       Plaque pattern is the most common type. Individual lesions are irregular, well demarcated and range from a few millimetres to several centimetres in diameter. The lesions are red with dry and thin silvery-white scaling, which may be obvious only after scraping the surface. The elbows, knees, lower back and scalp are most commonly involved.

       Guttate psoriasis (gutta is Latin for drop) is usually seen in children and adolescents. The rash resembling drops of dark red paint often appears rapidly and individual lesions are small and scaly. Bouts of guttate psoriasis usually clear in a few months, but patients may develop the plaque pattern later.

       Scalp is often involved, presumably due to repeated trauma from brushing and combing. Areas of marked scaling are interspersed with normal skin producing lumpiness which is more easily felt than seen.

       Nails are frequently involved with nail pitting, change in colour, subungual keratosis (thickening of the keratin layer under the nails) leading to onycholysis (separation of the nail from the nail bed).

       Flexures such as submammary and axillary folds show red, glistening and symmetrical changes which characteristically are not scaly.

       Erythrodermic psoriasis (exfoliative psoriatic dermatitis) is a less common but serious pattern where the skin becomes universally red, thick and scaly, with visible peeling. There is considerable increase in cutaneous blood flow and heat loss with characteristic compensatory shivering.

       There may be associated asymmetrical arthropathy affecting either the fingers and toes or a single large joint. This is called psoriatic arthritis; it often resembles rheumatoid arthritis and may be equally crippling.

Diagnosis:  < BACK TO TOP >

       Few tests are indicated. Biopsy of the skin may be carried out but is seldom necessary because the clinical picture is usually characteristic.

Management  < BACK TO TOP >

       Explanation and reassurance are always necessary to deal with patient’s concerns because anxiety sometimes can aggravate the disease.

       Treatment is related to reduction of epidermal cell turnover since there is no known cure.

       Mild lesions are usually treated with topical keratolytic agents (salicylic acid in a gel form).

       Topical coal tar preparations in form of cream or shampoo [Polytar, Alphosyl, Pinetarsol, Linotar, Alpha Keri Tar, Psorigel] probably act by inhibiting DNA synthesis and therefore cell proliferation.

       Topical steroids are usually reserved for the face, ears, genitalia and flexures, or for unresponsive psoriasis, but there is rapid relapse when they are withdrawn and in time they start to lose their efficacy. Common preparations are triamcinolone [Aristocort], fluocortolone [Ultralan], betamethasone [Diprosone, Betnovate, Celestone], halcinonide [Halciderm], mometasone [Elocon] and fluorometholone [Flucon, Flarex].

       Calcipotriol [Daivonex] is a non-steroidal antipsoriatic agent, derived from vitamin D that suppresses proliferation of epidermal cells (keratinocytes), thus reversing the abnormal keratinocyte changes in psoriasis; it is applied only topically in form of cream.

       UV radiation using medium-wave UV light (UVB) is often helpful, as well as sunbathing.

       Systemic treatments available today:

photochemotherapy with PUVA (photosensitising agent psoralen + UVA long-wave UV light) in specially designed cabins

retinoids-derivatives of vitamin A such as etretinate [Tigason] and actitretin [Neotigason] (they are teratogenic and potentially hepatotoxic)

methotrexate [Ledertrexate, Methoblastin] is as cytotoxic agent that seems to interfere with the rapid proliferation of epidermal cells and is used in extensive psoriasis; haematologic, hepatic and renal function should be monitored

Prognosis  < BACK TO TOP >

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Nutrition < BACK TO TOP >

Nutrition that alleviate or prevent Psoriasis :-
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Herbs < BACK TO TOP >

Herbs that alleviate or prevent Psoriasis :-
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