34 關於乾癬（psoriasis）的敘述，何者錯誤？

 關節炎可能是此病的皮膚外病徵（extra-cutaneous manifestation）

手肘及膝蓋是好發的部位之一

口服類固醇是首選治療法

Auspitz sign及Koebner phenomenon都是此病的表徵之一

remember this graph

we use topical steroid but not the systemic

Auspitz's sign is the appearance of punctate bleeding spots when psoriasis scales are scraped off, named after Heinrich Auspitz.^[1]

The Koebner phenomenon, also called the "Koebner response" or the "isomorphic response", refers to skin lesions appearing on lines of trauma.^[1] The Koebner phenomenon may result from either a linear exposure or irritation. Conditions demonstrating linear lesions after a linear exposure to a causative agent include: molluscum contagiosum, warts andtoxicodendron dermatitis (a dermatitis caused by a genus of plants including poison ivy). Warts and molluscum contagiosum lesions can be spread in linear patterns by self-scratching ("auto-inoculation"). Toxicodendron dermatitis lesions are often linear from brushing up against the plant. Causes of the Koebner phenomenon that are secondary to scratching rather than an infective or chemical cause include vitiligo, psoriasis, lichen planus, lichen nitidus, pityriasis rubra pilaris, and keratosis follicularis (Darier disease).

The Koebner phenomenon describes skin lesions which appear at the site of injury. It is seen in:^[2]

• Psoriasis
• Pityriasis rubra pilaris
• Lichen planus
• Lichen nitidus
• Vitiligo
• Lichen sclerosus
• Elastosis perforans serpiginosa
• warts