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Psoriasis

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AETIOLOGY AND RISK FACTORS

Abstract

 

VOL: 99, ISSUE: 20, PAGE NO: 28

Janet Blake, RN.

Community Nurse, Kingston, Surrey

 

AETIOLOGY AND RISK FACTORS

 


 

- Psoriasis is a common, non-infectious skin disease.

 


 

- There is a genetic predisposition to the condition, with 35 per cent of patients showing a family history.

 


 

PRECIPITATING FACTORS

 


 

- Infection, such as strep throat.

 


 

- Certain drugs.

 


 

- Sunlight.

 


 

- Hormones - psoriasis can become better or worse during pregnancy.

 


 

- Psychological stress.

 


 

- Trauma can create the Koebner effect where psoriasis is triggered in damaged skin such as in a surgical scar or at the site of a minor injury.

 


 

INCIDENCE

 


 

- Psoriasis is prevalent in two per cent of the UK population.

 


 

- It can affect any age group but usually occurs in early adult life.

 


 

- It is an unpredictable skin disorder with exacerbations and remissions.

 


 

PATHOPHYSIOLOGY

 


 

The plaques are caused by increased thickness of the epidermis and keratin layers of the skin due to rapid growth. The normal transit time of epidermal cells is about 27 days, whereas in psoriasis it is four days.

 


 

- Dilation of blood capillaries occurs and sometimes sterile pus is exuded due to the migration of white blood cells into the plaques.

 


 

- The patches vary in size from a few millimetres to centimetres.

 


 

SIGNS AND SYMPTOMS

 


 

- Non-itching, bright red or pink, sharply outlined, dry plaques with silvery/white scaling surfaces appear mainly on the elbows, knees, shins, scalp and lower back.

 


 

- The nails can also be affected and may be severely distorted. Pitting of nails and oncholysis (the distal edge of the nail separates from the nail bed) occurs. This is difficult to treat.

 


 

TYPES OF PSORIASIS

 


 

- Guttate - ‘drop-like’, symmetrical lesions on the trunk and limbs. Often triggered by a streptococcal throat infection. Responds well to therapy.

 


 

- Plaque - well-demarcated erythematous plaques covered in dry, white, waxy scales. Often localised to elbows and knees. Removal of this build-up leaves small bleeding points. Tends to be chronic, with exacerbations and remissions.

 


 

- Flexural - non-scaling psoriasis of the submammary, axillary and anogenital folds, commonly mistaken for candidiasis or tinea.

 


 

- Scalp - can be the sole manifestation of the disorder. Thick scales adhere to the scalp and behind the ears.

 


 

- Erythrodermic - rare and severe form where skin becomes bright red, and temperature control is difficult. The patient needs urgent hospitalisation.

 


 

- Pustular - a rare, localised form affecting soles and palms with sterile pustules, which dry to brown, scaly macules.

 


 

- Arthritis - psoriatic arthritis occurs in five per cent of patients, particularly on the fingers and toes. Rheumatoid factor tests are negative. Treatment requires the expertise of both a rheumatologist and a dermatologist.

 


 

DIAGNOSIS

 


 

- This is made from the clinical picture and relevant history.

 


 

- Tests may include a skin swab or biopsy, throat swab, routine blood test and removal of plaques to reveal pinpoint bleeding - the Auspitz sign.

 


 

TREATMENT

 


 

- Topical and systemic drug therapy, including vitamin D analogues, coal tar, dithranol and the retinoid tazarotene.

 


 

- Phototherapy - (UVB) is also effective and photochemotherapy which combines UVA and oral psoralen (an inhibitor of cell division).

 


 

NURSING IMPLICATIONS

 


 

- Psychological support, management of topical therapy and skilful clinical inpatient management may be required.

 


 

WEBSITE

 


 

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