<Things you should know> The correct knowledge about psoriasis: Causes, symptoms, and treatment of psoriasis What is psoriasis? Main types of psoriasis Diseases similar to psoriasis How psoriasis works Causes of psoriasis Treatment for psoriasis We explain common concerns related to psoriasis. Psoriasis, a disease that has been featured on health information programs and is attracting attention, is now a well-known name, but awareness of its symptoms and mechanisms of onset is still not very high. Therefore, with the supervision of a dermatologist, we will explain in detail the basic knowledge you should know about psoriasis. What is psoriasis? First, let's confirm the definition of psoriasis. What is psoriasis? Psoriasis is a chronic inflammatory skin disease. The incidence rate in Japan is estimated at 0.02-0.1%, with 100,000-200,000 patients. Although this is lower than the approximately 2% in Europe and the United States, the number of patients in Japan is gradually increasing. The male-to-female ratio is 2:1, with a higher incidence in men, and it most commonly develops in people in their 20s and 40s. Main symptoms Psoriasis is characterized by raised red patches of skin called "erythema" and silvery-white scales called "scaling." The erythema is raised, and the scales flake off. Friction and other irritants can cause the condition to spread to previously unaffected skin. Nail deformities and joint pain and deformation may also occur. Approximately half of patients experience itching. The condition may fluctuate, sometimes improving and sometimes worsening, but generally, symptoms tend to be milder in the summer and worsen in the dry winter months. Commonly seen areas Psoriasis can occur on the skin all over the body, but it is especially common on the head, knees, elbows, hips, buttocks, and nails. In the joints, symptoms such as joint pain may also occur. Areas where psoriasis is commonly found Main types of psoriasis Psoriasis is classified into five types depending on its condition: plaque psoriasis, guttate psoriasis, pustular psoriasis, erythrodermic psoriasis, and psoriatic arthritis. It can progress through the same type, change to a different type, or coexist with multiple types of psoriasis. plaque psoriasis Approximately 90% of psoriasis cases fall under the category of psoriasis vulgaris. It begins as small, raised red patches, which enlarge and merge to form red, raised lesions 1 to several centimeters in diameter. Silvery-white scales adhere to the surface of these lesions. It is particularly common in areas prone to irritation, such as the knees, elbows, scalp (especially the hairline), and buttocks. Nail deformities are also frequently observed. Guttate psoriasis Many small, keratinized, erythematous patches, less than 1 cm in size, appear on the trunk and the parts of the limbs closest to the trunk. In children, symptoms may appear throughout the body, sometimes triggered by a cold. While it progresses relatively rapidly, a characteristic feature is that the symptoms often subside within a few months. Pustular psoriasis This type of psoriasis is characterized by redness of the skin and the formation of many sterile pustules (blisters that become infected with pus). Pustular psoriasis can progress to or coexist with psoriasis vulgaris. When the pustules on the skin rupture, sores develop. Pustular psoriasis is classified as "localized" when symptoms appear only on parts of the body, such as the palms of the hands, soles of the feet, or fingertips. On the other hand, when pustules form all over the body, it is classified as "generalized," and is characterized by symptoms such as fever, general malaise, and swelling of the hands and feet. Generalized pustular psoriasis is severe, and especially during the "acute phase," when symptoms appear and progress rapidly, hospitalization is the basic treatment. psoriatic erythroderma This condition involves widespread skin symptoms of psoriasis, resulting in redness of the skin. It often progresses from plaque psoriasis or pustular psoriasis to erythrodermic psoriasis. Psoriatic arthritis This condition occurs in about 10-15% of psoriasis patients and is accompanied by arthritis characteristic of psoriasis. It most commonly affects the first joint (closest to the fingertip) and the second joint (next to the first joint), but symptoms can also appear in the shoulders, knees, elbows, and heels. In addition to swelling, throbbing pain, joint deformation, and stiffness may also be observed. In some cases, the joints can become permanently deformed, so early diagnosis and treatment are important. Diseases similar to psoriasis Psoriasis can present with symptoms similar to those of the following conditions. If you notice any abnormalities in your skin, see a dermatologist as soon as possible. seborrheic dermatitis Areas with high sebum secretion or friction, such as the head, face, and armpits, become red and develop eczema accompanied by yellowish scales. Itching is absent or mild. Seborrheic dermatitis is divided into "infantile seborrheic dermatitis," which is seen from the neonatal period to early infancy, and "adult seborrheic dermatitis," which is seen from puberty onward. Infantile seborrheic dermatitis usually resolves spontaneously by around the age of two, but adult seborrheic dermatitis tends to become chronic and recurs frequently. Related articles can be found here. nummular eczema Scattered or multiple red, slightly raised eczema patches, 1-5 cm in diameter, coin-shaped or nearly circular in shape, with clearly defined borders, appear on the hands and feet (especially from the knees to the ankles), trunk, and from the waist to the buttocks. The surface of the eczema may be moist and oozing. Scales are often present, and the area is intensely itchy. Related articles can be found here. How psoriasis works Next, let's look at how psoriasis develops. The surface of the skin is covered by a thin, tough layer called the "epidermis." Epidermal cells, born in the basal layer at the bottom of the epidermis, are gradually pushed upwards, becoming flattened keratinocytes, and eventually sloughing off as dead skin cells. This process is called skin metabolism (turnover), and in healthy skin, all cells are renewed in this way in a cycle of approximately 45 days. On the other hand, it has been found that the metabolic cycle in psoriatic skin is extremely short, ranging from 4 to 7 days. This accelerated cycle leads to the excessive production of keratinocytes, causing scales to form one after another. In addition, the epidermis and the dermis beneath it contain an increase in blood components such as white blood cells and inflammatory substances, which can cause the skin to become red, raised, and itchy. How psoriasis works Causes of psoriasis The underlying cause of psoriasis is still not fully understood, but it is believed that a combination of factors, including a predisposition to psoriasis, leads to an abnormality in the immune system, resulting in the development of psoriasis. Factors that can trigger psoriasis include the following: Genetic factors Psoriasis is thought to be genetic, meaning it is based on one's inherent constitution, and several genes that predispose individuals to psoriasis have been identified. The incidence of developing psoriasis in families with a history of the condition in Japan is estimated to be 4-5%. External factors External factors such as external stimuli, infections, diet, alcohol consumption, and smoking can also trigger psoriasis. Internal factors Psoriasis is often associated with metabolic syndrome, which includes obesity, high blood pressure, diabetes, and dyslipidemia, and metabolic syndrome is thought to be involved in the development of psoriasis. Treatment for psoriasis There are two main approaches to managing psoriasis: "medical treatment at a hospital" and "self-care." Hospital treatment To prevent psoriasis from worsening, it is very important to visit a hospital with a dermatologist as soon as possible and receive appropriate treatment. There are four main types of treatment for psoriasis: topical therapy (ointments), phototherapy (ultraviolet therapy), oral therapy (drugs), and injection therapy. Because psoriasis often involves periods of improvement and worsening, the treatment method is selected according to the state of the disease and the patient's condition. Treatment methods for psoriasis Adapted from: Iizuka, Hajime: J Visual dermatol 16(9), 850-851, 2017. The diagram above illustrates treatment methods, with the severity of psoriasis increasing from top to bottom. Treatment primarily involves controlling the symptoms of psoriasis using topical medications. Biological agents, which have been available in Japan since 2010, are a treatment method that uses injections to target and suppress substances that cause psoriasis. While they are not effective for all patients, they are attracting attention for their effectiveness in many cases. If you wish to receive treatment with biological agents, you must visit a hospital designated by the Japanese Dermatological Association. Self-care in everyday life In addition to hospital treatment, please be mindful of the following points in your daily life. Avoid skin irritation Avoid rubbing your skin or forcibly peeling off scales, as this can worsen psoriasis. To avoid irritating and aggravating symptoms, wear soft, loose-fitting clothing. Also, be careful not to rest your elbows or knees on surfaces or sit in a kneeling position for extended periods, as these can also strain the skin. Pay attention to how you wash yourself when bathing. Bathing and showering are important for maintaining cleanliness, but it's important not to scrub your body and scalp too hard. Rinse thoroughly to ensure no residue remains, and after bathing, use an absorbent towel to gently pat dry without rubbing. Moisturize your skin to prevent it from drying out. Dry skin is also one of the factors that worsen symptoms. Make sure to properly moisturize your entire body with a moisturizer to protect your skin from dryness. Get some sunlight in moderation Moderate sun exposure can help improve the symptoms of psoriasis. However, excessive exposure to ultraviolet rays can worsen psoriasis, so be sure to limit your sun exposure to avoid getting sunburned. Be careful about obesity. Limit your intake of foods high in fat and sugar, and make moderate exercise a regular habit. Refrain from drinking alcohol and smoking. Excessive alcohol consumption and smoking habits negatively impact psoriasis. Be mindful not only of your own smoking but also of secondhand smoke from those around you. Don't let stress build up. Stress can worsen the symptoms of psoriasis. Try to incorporate ways to manage stress, such as making time to immerse yourself in a hobby. Get quality sleep Getting enough quality sleep is also helpful in managing psoriasis. Before going to bed at night, avoid using bright lights such as televisions and smartphones, and spend time relaxing to promote restful sleep. We explain common concerns related to psoriasis. This article addresses common concerns about psoriasis. Is psoriasis contagious? Before starting treatment, some patients worry that psoriasis might spread to those around them, or that they should avoid bathing in the same bathroom as their family. However, psoriasis is not contagious. Can psoriasis be cured? Psoriasis is a difficult disease to treat, but it can be controlled with treatment. Some patients even manage to stay symptom-free for extended periods. The symptoms of psoriasis vary from person to person, and the concerns they face are also different. For example, for a patient who wants to wear black clothes but is bothered by the noticeable scales resembling dandruff, adjusting the medication applied to the scalp, for instance, can help reduce the inconvenience in their daily life by choosing a treatment method tailored to their specific concerns. If you have any concerns, please consult a dermatologist. Supervised by: Professor Akira Kawada, Chief of the Department of Dermatology, Kinki University Faculty of MedicineAfter graduating from Tokyo Medical and Dental University School of Medicine, he held positions as a lecturer in dermatology at the National Defense Medical College, associate professor in dermatology at Teikyo University Ichihara Hospital, and associate professor in dermatology at Kinki University School of Medicine before assuming his current position. He is a certified dermatologist and instructor by the Japanese Dermatological Association and the Japanese Society for Laser Medicine. He is a member of the Japanese Dermatological Association, the Japanese Society for Laser Medicine, the Japanese Psoriasis Society, the American Academy of Dermatology, and the European Association for Dermatology and Dentistry. We take care to post accurate information,Please point out any incorrect information. Please submit any comments regarding medical information here. 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