Psoriasis داء الصدفية

Definition :common,chronic,disfiguring, inflammatory and proliferative condition of the skin. -population prevalence varies between 0.3%-3%.considerable racial variation. Age of onset: -has bimodal distribution of age of onset; early peak between 16 &22,and the later one at 57-60 years.

Aetiology : 1-Genetic epidemiology: - The risk for a child to develop psoriasis is 14% if one parent is affected.41% if two parents are affected. & 6%if one sibling is affected. Compared to 2% when no parent or sibling Is affected. heridetary,strongly HLA associated (HLA_Cw6).

2-Environmental risk factors: A-trauma : Trauma to the skin can precipitete ps. In traumatized skin , called koebner phenomenon. B-infection: streptococcal infection has important role ,esp. in guttate psoriasis. C-Drugs: lithium salts, anti- malarials ,β- blockers, NSAID,ACE inhibitors. D-sunlight; generally beneficial ,but strong light may be a provoking factor. E-metabolic factors :hypocalcaemia ppt. ps. f-Psychogenic factors :it is believed to play imprtant role in ps. g:hormonal factors : frequently imprives in pregnency only to relapse postpartum.

-epidermal lymphocyte&neutrophile Pathosenesis : There is a rapid turnover of basal layer to stratum corneum. Normally transit time of proliferation is about 30-60 day but in ps. It reduced to 3 day,the basal cell will retain their nuclei in cornified layer ( parakeratosis ) Pathology : -parakeratosis -acanthosis :irregular thickening of Epidermis. -no granular layer -epidermal lymphocyte&neutrophile Infiltrate (micro-abscesses) -dilated &tortuous capillary loops in Dermal papillae. -

Koebner phenomenon : in psoriasis Also occurs in lichin planus – erythema multiforme –vitiligo –viral wart Auspitz sign :bleeding occur when scale is scratched off.

Clinical feature : Ps varies in severity from chronic stable ps to life threatening (like acute generalized pustular ps or erythrodernic ps ) Ps is characterized by a base of erythrodermic plaques covered by silvery scales mainly on the extensor surface on elbows & knees .

-clinical variets : 1-plaque ps ( ps vulgaris ): plaque ,red (salmon pink) colour,well define edge. Scale, Very characteristic is silvery white scales varying in thickness. Plaques are of variable sizes and shapes. And number, may be symmetrically distribution.

2-guttate ps : acute symmetrical ,mostly seen in adolescent ,may follow streptococcal tonsilitis. 3- flexural ps : affect axilla ,submammary, groin. The plaque are red smooth ,non scally & glazed.

4-Pustular ps: -localized pustular ps : usually palmoplantar pustulosis with haemorrhagic crust &scale involving the instep & palm usu. Seen in smokers. -generalized pustular : it is life threatening ,acute generalized erythroderma studded with pustules.

5-erythrodermic ps :life threatening condition ,in which the body is red ,>90% of body surface area, less scaly 6-psoriatic arthropathy : 5% of the patients have ps arthritis -distal terminal interphalangeal joints of hand &feet -RA like arthritis ( polyarthropathy) -AS like arthritis :(spine involve &sacroilitis) -arthritis mutilans :severe involvement of hands with deformity.

7-nail ps. : 50 % -onycholysis :seperation of distal edge of nail from bed. -pitting (common) -oil spots -subungual hyperkeratosis -splinter hg. -dystrophy

8-scalp ps : the scalp is often involved. Prognosis : Unpredictable in general. Intractable disease but rarely dangerous to life. Guttate attacks have better prognosis Pustular and erythrodermic carry appreciable mortality Psoriatic arthropathy forms considerable morbidity. Early onset and family history worsen prognosis. Complete remissions over 1-54 years were reported in 39% of patients.

Management: 1-general measure :social support ,eradication of infection &treatment of precipating factors . 2-therapeutic measures: a-topical : -topical steroids: moderate to potent e.g. flucinolone,flumetasome, betamethasone.we should avoid very potent steroid e.g. clobetasol because it may cause rebound severe reaction. -keratolytics :e.g salicylic acid 3% to remove the scale . -crude coal tar: smelly ,messy & stain clothes -calcipitriol (vit D3 derivative ):for mild to moderate ps. Affecting less than 40% of the skin. b-phototherapy: (PUVA & UVB ): the equipment should be serviced & calibrated regularly by trained personnel.

C-systemic : 1-retinoids (vit A derivative ) : Acitretin is effectinve in plaque & palmoplantar ps. S.E : -teratogenic : in female should not concept for at least 2year after stoppage of drug. -dryness of skin & mucous mem. -hyperlipdemia 2-methotrexate : for severe ps. ,it has anti-inflammatory &immune modulatory effects , given once weekly (oral or I.M ).improvement is seen in 2-4 weeks. liver function test ,CBP should be monitered . drug interaction with asprin ,NSAID , CO-Trimaxazole. S.E : nausea, vomiting ,hepatotoxicity ,teratogenicty & pulmonary fibrosis.

3-cyclosporin : is immunosoppresant ,effective in sever ps 3-cyclosporin : is immunosoppresant ,effective in sever ps. Act by inhibiting T-lymphocyte activities .hypertention is common S.E. ,nephrotoxic (dose dependant) 4-Biological drugs : e.g Infliximab , Etanercept..etc very effective & safe but very expensive.