Psoriasis, commonly known as psoriasis, is a common chronic, inflammatory, recurring skin disorder characterized by the appearance of erythematous patches, papules, and plaques of varying sizes covered with silvery-white scales with clear borders, and bleeding spots when the silvery-white scales peel off. It occurs on the scalp, extensor surfaces of the limbs and back. Although psoriasis does not directly affect life, it can have a very serious impact on physical health and mental and physical health.
Causes and pathogenesis of psoriasis
The exact cause of psoriasis is not yet known. It is currently believed that psoriasis is a polygenic genetic disease in which genetic and environmental factors and other factors interact to cause excessive proliferation of keratin-forming cells through a T-cell-mediated immune response.
I. Genetic factors
Epidemiology, HLA analysis and whole gene scan analysis all support the genetic predisposition of psoriasis. 20% of psoriasis has a family history, and when one parent has psoriasis, the incidence of psoriasis in children is about 16%; while when both parents are psoriasis patients, the incidence of psoriasis in children reaches 50%. and Cw6 and class II antigen DR7 are expressed more frequently in patients with psoriasis than in normal subjects, with the Cw6 locus being the most clearly associated with psoriasis. Since 1994, eight loci have been identified by genome-wide scans for psoriasis susceptibility genes located in regions 1p, lq, 3q, 4q, 6p, 17q, 19p, etc.
Second, environmental factors
Genetic factors alone are not enough to cause the onset of psoriasis, but environmental factors play an important role in triggering and aggravating psoriasis. Factors that can trigger or aggravate psoriasis include infection, mental stress and stressful events, trauma, surgery, pregnancy, smoking and the effects of certain drugs, among which infection has always been considered an important factor in triggering or aggravating psoriasis, for example, there is often a history of acute streptococcal infection in the pharynx before the onset of psoriasis, and the condition often improves after antibiotic treatment is given.
Three, immune factors
Lymphocyte and monocyte infiltration at the lesions of psoriasis vulgaris is obvious, especially T-lymphocyte dermal infiltration is an important pathological feature of psoriasis, indicating that the immune system is involved in the occurrence and development of the disease. It is hypothesized that activated T lymphocytes in the lesions release cytokines (IL-1, -6, -8, IFN-γ, etc.) that stimulate keratinocyte proliferation and promote and participate in the development of psoriasis. An important feature of the pathophysiology of psoriasis is the accelerated proliferation of keratin-forming cells in the basal layer of the epidermis, the shortening of the mitotic cycle to 37.5 hours, the shortening of the epidermal turnover time to 3-4 days, and the histopathological appearance of incomplete keratinization and the disappearance of the granular layer.
What are the clinical manifestations of psoriasis?
According to the clinical features of psoriasis, it can be divided into common type, arthritic type, pustular type and erythrodermic type, among which common type accounts for more than 97%. Other types are mostly transformed from common psoriasis, which can be induced by the external use of stimulating drugs, systematic use of glucocorticoids, sudden discontinuation of drugs during immunosuppression, as well as infection and mental stress.
Psoriasis vulgaris
Arthritic psoriasis
Pustular psoriasis
Erythrodermic psoriasis
Psoriasis vulgaris: The initial lesions are red papules or macules, which gradually expand into red plaques with clear boundaries and can take many forms (such as drip, plaque, coin, map, oyster shell, etc.), covered with thick layers of silvery white scales, scraping away the layers of scales as if lightly scraping wax drops (wax drop phenomenon), and scraping away the silvery white scales to reveal light red glowing Translucent film (film phenomenon), peel off the film can be seen dotted bleeding (Auspitz sign), the latter is caused by the top of the dermal papillae tortuous dilated capillaries are scraped.
Wax drop phenomenon, film phenomenon and punctate hemorrhage have diagnostic value for psoriasis. The lesions can occur all over the body but are most common on the extremities, especially on the elbows, knees and sacrococcygeal region, and are often symmetrical, with differences in different parts of the skin.
Psoriasis vulgaris can be divided into three stages according to the development of the disease.
Progressive phase: old lesions do not fade, new lesions keep appearing, infiltrative inflammation of the lesions is obvious, there may be a red halo around, and the scales are thick; injuries such as needling, scratching and surgery can lead to the appearance of typical psoriatic lesions on the damaged area, called isomorphism or Kobner’s phenomenon.
Resting phase: stable lesions, no new lesions appear, less inflammation and more scaling.
Degenerative phase: lesions shrink or flatten, inflammation largely subsides, and hypopigmentation or hyperpigmented spots remain. Acute guttate psoriasis, also known as eruptive psoriasis, is common in young people and is often preceded by a history of streptococcal infection of the throat. The lesions are 0.3~0.5cm sized papules and macules, flushed and covered with a few scales, with varying degrees of itchiness. With appropriate treatment, the lesions may subside within a few weeks, and in a few patients, the disease may become chronic.
Differential diagnosis of psoriasis
Diagnosis and typing are mainly based on typical clinical manifestations, and histopathological manifestations have a certain diagnostic value.
Psoriasis should be differentiated from the following diseases.
1. seborrheic dermatitis: distinguish it from scalp psoriasis. The lesions are erythematous with indistinct edges. It is covered with fine yellow greasy scales, and the hair can be sparse, thin and fall out, but there are no bundles of hair.
2. Headache: Differentiate from scalp psoriasis. The lesions are covered with grayish white bran-like scales, with hair breakage and hair loss Easy to detect fungi, mostly seen in children.
3. Phase II syphilis rash: history of unclean sexual intercourse and hard chancre, typical lesions are coppery red, infiltrative rash or maculopapular rash on palmoplantar area, positive for syphilis seropositivity.
4. lichen planus: the lesions are polygonal flat purple-red papules that can fuse into scaly plaques, with mucous membranes often involved and a chronic course.
5, chronic eczema: differentiate from hypertrophic psoriatic lesions occurring on the lower legs, extensor aspect of the forearms and sacrococcygeal region. Eczema often has intense itching and the skin is infiltrated with hypertrophic, mossy changes.
Clinical treatment of psoriasis
Treatment of psoriasis can only achieve clinical remission and is not yet curative. Treatment should prohibit irritating topical drugs, as well as drugs that can lead to serious adverse reactions (such as the systematic use of glucocorticoids and immunosuppressants), so as not to aggravate the disease or transform it to other types. The appropriate treatment should be given for different causes, types and stages of the disease, and psychotherapy should be emphasized. Avoid triggering or aggravating factors such as upper respiratory tract infection, exertion and mental tension.
Treatment principles of psoriasis.
The purpose of psoriasis treatment is to control the disease, slow down the process of development to the whole body, reduce symptoms such as erythema, scaling and local patch thickening, stabilize the disease, avoid recurrence, avoid side effects as far as possible and improve patients’ quality of life. Communication with patients and assessment of their conditions during treatment is an important part of treatment. When the effect of single therapy is not obvious in patients with moderate or severe psoriasis, combined, rotating or sequential therapy should be given.
Topical drug treatment: glucocorticoid cream or ointment has obvious efficacy, but attention should be paid to its adverse reactions. Long-term application of strong or super-potent preparations in a large area may cause systemic adverse reactions, and may even induce pustular or erythrodermic psoriasis after stopping the drug; vitamin A acid cream is commonly used at a concentration of 0.025%-0.1%, of which 0.05%-0.01% tazarotene gel is more effective in treating plaque psoriasis Vitamin D3 derivatives such as calcipotriol also have good efficacy, but should not be used on the face and skin folds; various keratin-enhancing agents (such as tar preparations, anthralin ointment, 10%-15% camptothecin ointment, salicylic acid ointment, etc.) can also be used.
Systemic treatment: retinoic acid drugs are suitable for all types of psoriasis, such as aveloxate 0.75~1.0mg/(kg-d) orally; immunosuppressants are mainly suitable for erythrodermic, pustular and arthritic psoriasis, commonly used are methotrexate in adult doses of 10~25mg orally per week, cyclosporine and tacrolimus are also available; patients with obvious infection or generalized pustular psoriasis should use Antibiotics; glucocorticoids are generally not advocated for common psoriasis, but mainly used for erythrodermic psoriasis, acute arthritic psoriasis and generalized pustular psoriasis, etc. The dose can be reduced by combining with immunosuppressants and retinoids, and should be applied for a short period of time and gradually reduced to prevent the condition from rebounding; immunomodulators can be used for those with low cellular immune function.
Physical therapy: such as photochemotherapy (PUVA), UVB phototherapy (especially narrow-wave UVB), bath therapy, etc. can be applied.