What Is Psoriasis?

Psoriasis is a chronic skin condition in which many red, raised lesions form on the skin. The redness has a clear border and is round or oval in shape, or several merge into a large patch. The surface is covered with dry, white scale and feels rough. It tends to appear in places where the skin is prone to friction and pressure, mainly the elbows, kneecaps, scalp, the back—especially around the waist—and, on the face, the forehead, and it may be itchy. Bumpy depressions can also form on the fingernails and toenails.

Psoriasis has a higher prevalence in Westerners than in Japanese people, and in Japan there are about twice as many male patients as female patients.

The cause of psoriasis is not completely understood, but whereas the turnover of the epidermis normally takes about 45 days, in psoriatic skin the turnover is extremely shortened, to four to seven days.

The most common type of psoriasis is called psoriasis vulgaris. When the psoriatic eruptions are accompanied by arthritis, it is called arthropathic psoriasis, or psoriatic arthritis, and it is necessary to treat it firmly, in cooperation with orthopedics, so that joint deformity does not occur.

Treatments for Psoriasis

The treatment of psoriasis differs according to the severity of symptoms, which part of the body it appears on, and any complications.

Treating lifestyle-related diseases

Psoriasis is inflammation of the skin, but it has come to be known to be related to internal inflammation such as high blood pressure, diabetes, dyslipidemia, and obesity.

If you were advised to see a doctor because your blood sugar or cholesterol was high at a health check-up but left it alone, we recommend taking the diagnosis of psoriasis as an opportunity to see an internist and receive the necessary treatment. If you wish, we can also refer you from our clinic to an appropriate medical institution.

Topical therapy (creams and ointments)

For mild cases, we first treat with topical steroids and topical vitamin D3. Steroids are drugs that suppress inflammation, and vitamin D3 preparations are drugs that suppress the dryness and roughness; using both at the same time is more effective.

Steroids

For areas other than the face, the strongest class of steroids is often used, such as Dermovate® (clobetasol propionate) ointment/cream and Diacort® (diflorasone diacetate) ointment/cream. A side effect of steroids is secondary infection.

Vitamin D3 preparations

These include Oxarol® (maxacalcitol) ointment/lotion and Dovonex® (calcipotriol) ointment. As a side effect of vitamin D3 preparations, the calcium concentration in the blood can rise. This rarely happens as long as you apply the prescribed amount, but it can occur depending on the combination with oral drugs prescribed by another medical institution such as internal medicine or orthopedics, and because it can cause gastrointestinal symptoms and impaired kidney function, caution is needed.

Combination drugs of steroid and vitamin D3

Because applying two types can be a hassle, there are also combination topical drugs that mix the steroid and the vitamin D preparation. (However, the steroid strength is the second class from the top.) These include Marduox® (a maxacalcitol / betamethasone butyrate propionate combination) ointment and Dovobet® (a calcipotriol hydrate / betamethasone dipropionate combination) ointment/gel/foam, and patients who dislike stickiness may find the foaming spray-type Dovobet® Foam easy to use.

Vtama® (tapinarof) cream

A drug that has appeared recently. It has an action that suppresses skin inflammation and also enhances the barrier function, and it is used not only for psoriasis but also for atopic dermatitis. As a side effect, surprisingly for a topical medication, there is headache. Others include irritation and acne.

The features of the topical drugs used for psoriasis are summarized in the table below.

Ultraviolet phototherapy

When topical drugs cannot fully suppress the symptoms, we use ultraviolet phototherapy.

Tamachi Ekimae Dermatology, Clinica Riviera Shibaura, has introduced the following two types of ultraviolet treatment device.

Daavlin 7 (narrow-band UVB)

Suited to those with red eruptions over a wide area. Irradiation is performed standing, in two sessions for the front and back.

FlexSys Fit 100 (excimer light)

Suited to those with red eruptions in limited areas, such as the elbows, knees, hands and feet, and the hairline of the scalp. Because pinpoint irradiation is possible, treatment is possible while limiting the effect on healthy skin. It can also be effective on nail symptoms.

In both cases, the irradiation itself takes only a few minutes. We adjust the strength while watching the reaction to the previous irradiation. Those who can find the time should receive treatment two or three times a week, and busy people about once every two weeks. Side effects of ultraviolet phototherapy include the skin turning red as if burned, becoming raw, developing pigmentation, the risk of skin cancer, and photoaging.

Learn more about ultraviolet phototherapy

Oral therapy (medications taken by mouth)

For moderate-to-severe psoriasis vulgaris, oral treatment may be used.

Vitamin A derivative

A drug called Tigason® (etretinate) capsules, taken after meals in one to three divided doses per day. It acts to thin the thick keratin, but because it is an oral drug, it acts not only on the affected area but also on normal areas of skin and mucous membranes.

Side effects include dry skin, cheilitis, hair loss, impaired liver function, and elevated blood lipids. Because it is teratogenic, it cannot be taken by women who are pregnant or who may be pregnant. Women must use contraception for at least two years after stopping the drug, and men for at least six months. Because of its strong side effects, its use has decreased with the advent of the biologic drugs described later.

Immunosuppressant

A drug called Neoral® (cyclosporine) capsules / oral solution, which suppresses immunity by interfering with lymphocytes. The dose is adjusted while regularly checking the blood concentration, and it is taken twice a day, morning and evening. It has many side effects, such as impaired kidney function, impaired liver function, high blood pressure, high blood lipids, gum overgrowth, and infections due to reduced immunity, and its use has decreased with the advent of the biologic drugs described later.

PDE4 inhibitor

A drug called Otezla® (apremilast), which suppresses the working of the cells that cause inflammation by inhibiting a molecule called phosphodiesterase (PDE) 4. You start with a small dose, gradually increase it, and ultimately take a fixed dose twice a day. Side effects can include nausea, diarrhea, decreased appetite, headache, fatigue, and low mood. Gastrointestinal symptoms often improve with the concurrent use of stomach medicine or a digestive regulator, and once you get used to it, these may no longer be needed.

TYK2 inhibitor

A drug called Sotyktu® (deucravacitinib) tablets. It is a new type of oral drug that, by binding to a molecule called tyrosine kinase 2 (TYK2), prevents TYK2 from being activated and suppresses the inflammatory response. It is taken once a day, regardless of meals. Side effects include upper respiratory infection, herpes simplex, and shingles. Because it has an action that suppresses immunity, caution is needed for those who have had tuberculosis, carriers of the hepatitis B virus, and so on.

The features of the oral drugs used for psoriasis are summarized in the table below.

Biologic drugs (injectables)

When symptoms cannot be controlled despite firm treatment with topical drugs, ultraviolet phototherapy, and so on, or when there are also joint symptoms, we use a type of drug called a biologic. Because it has an immunosuppressive action and carries a risk of suppressing even the immunity that is beneficial to the body, its use is limited to severe patients. The cost is also high, but the burden can be reduced through the High-Cost Medical Expense Benefit system. Patients for whom starting a biologic is considered desirable will be referred, as they wish, to a general hospital, university hospital, or the like.