I. Scalp psoriasis: scalp psoriasis can occur alone or at the same time as trunk and extremity psoriasis, but in most cases scalp lesions appear before trunk and extremity lesions, at this time, differential diagnosis is very important. 1, bundle hair: This is the characteristic lesion of scalp psoriasis, which is manifested as scaly erythema of the scalp, on which the hair is bundled, but no hair loss occurs. When this lesion appears, the diagnosis of psoriasis can be basically established. 2, asbestos-like furfur: the performance of thick scales on the scalp, asbestos-like appearance. There are various views on the attribution of asbestos furfur: some scholars think it is an independent disease; some think it is seborrheic dermatitis. According to my observation, such lesions often appear with trunk and limb psoriasis, which should be the performance of psoriasis. 3, forehead hairline erythema: forehead hairline erythema is also one of the manifestations of scalp psoriasis. 4. Diffuse erythema of the scalp: sometimes the scalp lesions are fused into patches or even covered with scalp. Mucous membrane psoriasis: it often occurs on the glans and inner surface of the foreskin, and can also be seen in the mouth and conjunctiva. The manifestation is a smooth and dry erythema with clear boundaries on the inner surface of the glans and foreskin, with white scales when scraped. Occurring in the buccal mucosa, hard palate, gums, tongue and other places oral damage is creamy white, gray-white, or gray-yellow papules or ring-shaped patches, basal infiltration, surrounding red halo, surface impregnation vesicles, or map tongue. Third, diaper psoriasis: specifically seen in infants aged 2-8 months, manifesting as bright red, well-defined patches in the diaper area, which may subside with local treatment of the lesions, but psoriatic damage may appear in adulthood. Fourth, palmoplantar psoriasis: can be seen in the palmoplantar alone, but also with other parts of psoriasis at the same time. It is manifested as palmoplantar keratinized plaques with clear boundaries, and the plaques can be dotted with white scales or dotted depressions, which can cause chaps due to thicker skin lesions. V. Nail psoriasis: proximal nail matrix keratinization insufficiency leads to thimble-like nail changes; the middle nail matrix is involved to form white nails; if the whole nail matrix is involved, the nail will have a white fragile appearance and easily fall off. The distal nail bed is hyperkeratotic, resulting in yellow spots on the nail with an “oil spot” or “oil drop” appearance. Hyperkeratotic thickening under the nail resembles nail fungus. In addition, nail clouding, nail transverse groove, nail longitudinal ridge, nail plate unevenness, nail separation, or the entire nail plate deformity may also appear. Sixth, flexural psoriasis (reverse psoriasis, reverse-transformation psoriasis): psoriasis lesions are normally distributed on the trunk and the extensor side of the limbs, but if only the flexural side of the limb is involved behind the ear, under the breast, axilla, groin, hip groove and other parts, it is called flexural psoriasis, also known as “reverse psoriasis”, or “reverse-transformation psoriasis”. reverse psoriasis”, or “anti-transition psoriasis”. Unilateral psoriasis: psoriasis lesions are generally symmetrical in distribution, and if only the limbs are involved unilaterally, it increases the difficulty of differential diagnosis. Recently, it has been reported that psoriasis lesions can appear at the calves of varicose veins; psoriasis damage can appear at the site of previous herpes zoster.