Psoriasis

Picture of scalp psoriasis. Source: iStock.com.

Psoriasis is a noncontagious, chronic skin disease that produces plaques of thickened, scaly skin. The dry flakes of silvery-white skin scales result from an excessively rapid production of skin cells. Psoriasis is fundamentally a defective inflammatory response. The proliferation of skin cells is triggered by inflammatory chemicals produced by specialized white blood cells called T-cells. Psoriasis commonly affects the skin of the elbows, knees, and scalp.

The spectrum of this disease ranges from mild with limited involvement of small areas of skin to severe, with large, thick plaques to red inflamed skin affecting the entire body surface.

Psoriasis is considered an incurable, long-term (chronic) inflammatory skin condition. It has a variable course, periodically improving and worsening. It is not unusual for psoriasis to spontaneously clear for years and stay in remission. Many people note a worsening of their symptoms in the colder winter months.

Psoriasis affects all races and genders. Although psoriasis can be seen in people of any age, from babies to seniors, most commonly patients are first diagnosed in their early adult years. The self-esteem and quality of life of patients with psoriasis are often diminished because of the appearance of their skin. Recently, it has become clear that people with psoriasis are more likely to have diabetes, high blood lipids, cardiovascular disease, and a variety of other inflammatory diseases. This may reflect an inability to control inflammation. Caring for psoriasis takes medical teamwork.

Picture of plaque psoriasis on the legs. Source: iStock.com.

The types of psoriasis include:

• Plaque psoriasis: Plaque psoriasis typically affects elbows, knees, scalp, and lower back, but can also affect palms, soles of feet, navel region, and nails. Plaque psoriasis is marked by red, raised, and inflamed skin lesions with silvery, flaky scales that can itch, burn, and bleed.
• Guttate psoriasis: Guttate psoriasis, more common in children and young adults, often occurs after a respiratory infection such as strep throat. Guttate psoriasis occurs predominantly on the torso, arms, and legs, and produces individual, pink, scaly spots that can itch severely.
• Inverse psoriasis: Inverse psoriasis forms red, shiny, smooth lesions, typically in the skin folds in the armpits, groin, buttocks, and under the breasts.
• Pustular psoriasis: Pustular psoriasis is marked by non-infectious fluid-filled pustules on the palms and soles, but in rare cases, it can be generalized all over the body and may require hospitalization.
• Erythrodermic psoriasis: Erythrodermic psoriasis is a rare and severe form of psoriasis that can affect the entire body, causing the skin to peel off in sheets, accompanied by pain and itching.
• Scalp psoriasis: Scalp psoriasis occurs in approximately 50% of psoriasis patients. Scalp psoriasis causes skin flaking, intense itching, thick scalp sores, and hair loss that can extend to the forehead, hairline, back of the neck, and behind the ears.
• Nail psoriasis: Nail psoriasis causes discoloration, pitting, and crumbling of nails, and occurs in about 50% of psoriasis patients.
• Oral psoriasis: Oral psoriasis occurs along with skin psoriasis in some people and causes red patches in the tongue, ulcers in the mouth, and cracked, bleeding lip corners.
• Napkin psoriasis: Napkin psoriasis is rare and occurs in the diaper region of children up to two years. Napkin psoriasis is usually guttate psoriasis and can be mistaken for diaper rash.
• Linear psoriasis: A rare form of psoriasis that forms in a linear distribution on the skin.
• Psoriatic arthritis: Psoriatic arthritis, which mostly inflames the joints in hands and feet, usually develops in people who have had psoriasis for a relatively long period.

Occasionally, it can be difficult to differentiate eczematous dermatitis from psoriasis. This is when a biopsy can be valuable to distinguish between the two conditions.

• Both eczematous dermatitis and psoriasis often respond to similar treatments.
• Certain types of eczematous dermatitis can be cured, which is not the case for psoriasis.

The exact cause of psoriasis remains unknown. A combination of elements, including genetic predisposition and environmental factors, are involved. It is common for psoriasis to be found in members of the same family. Defects in the immune system and the control of inflammation are thought to play major roles. Certain medications such as beta-blockers have been linked to psoriasis. Despite research over the past 30 years, the "master switch" that turns on psoriasis is still a mystery.

Although psoriasis is not contagious from person to person, there is a known hereditary tendency and a family history is very helpful in making the diagnosis.

Psoriasis is a fairly common skin condition and is estimated to affect approximately 2%-3% of the U.S. population. It currently affects roughly 8 million people in the U.S. It is seen worldwide by about 125 million people. African Americans have about half the rate of psoriasis as Caucasians.

Guttate psoriasis symptoms and signs include bumps or small plaques of red itchy, scaling skin that may appear explosively, affecting large parts of the skin surface, after a sore throat.

The symptoms and signs of psoriasis depend on the type, which may include:

• Plaque psoriasis
  • Plaque psoriasis signs and symptoms appear as red or pink small scaly bumps that merge into plaques of raised skin. Plaque psoriasis classically affects skin over the elbows, knees, and scalp and is often itchy. Although any area may be involved, plaque psoriasis tends to be more common at sites of friction, scratching, or abrasion. Sometimes pulling off one of these small dry white flakes of skin causes a tiny blood spot on the skin. This is a special diagnostic sign in psoriasis called the Auspitz sign.
• Nail psoriasis
  • Fingernails and toenails often exhibit small pits (pinpoint depressions) and/or larger yellowish-brown separations of the nail from the nail bed at the fingertip called distal onycholysis. Nail psoriasis may be confused with and incorrectly diagnosed as a fungal nail infection.
• Guttate psoriasis
  • Guttate psoriasis symptoms and signs include bumps or small plaques (½ inch or less) of red itchy, scaling skin that may appear explosively, affecting large parts of the skin surface simultaneously, after a sore throat.
• Inverse psoriasis
  • In inverse psoriasis, genital lesions, especially in the groin and on the head of the penis, are common. Psoriasis in moist areas like the navel or the area between the buttocks (intergluteal folds) may look like flat red plaques without much scaling. This may be confused with other skin conditions like fungal infections, yeast infections, allergic rashes, or bacterial infections.
• Pustular psoriasis
  • Symptoms and signs of pustular psoriasis include the rapid onset of groups of small bumps filled with pus on the torso. Patients are often systemically ill and may have a fever.
• Erythrodermic psoriasis
  • Erythrodermic psoriasis appears as extensive areas of red skin often involving the entire skin surface. Patients may often feel chilled.
• Scalp psoriasis
  • Scalp psoriasis may look like severe dandruff with dry flakes and red areas of skin. It can be difficult to differentiate between scalp psoriasis and seborrheic dermatitis when only the scalp is involved but the treatment is often very similar for both conditions.

Picture of psoriasis on the hands. Source: iStock.com.

Psoriasis is associated with inflamed joints in about one-third of those affected. Sometimes joint pains may be the only sign of the disorder, with completely clear skin. The joint disease associated with psoriasis is referred to as psoriatic arthritis. Patients may have inflammation of any joints (arthritis), although the joints of the hands, knees, and ankles tend to be most commonly affected. Psoriatic arthritis is an inflammatory, destructive form of arthritis and needs to be treated with medications to stop the disease progression.

The average age for onset of psoriatic arthritis is 30-40 years of age. Usually, the skin symptoms and signs precede the onset of arthritis.

Psoriasis may involve solely the nails in a limited number of patients. Usually, the nail signs accompany the skin and arthritis symptoms and signs. Nail psoriasis is typically very difficult to treat. Treatment options are somewhat limited and include potent topical steroids applied at the nail-base cuticle, injection of steroids at the nail-base cuticle, and oral or systemic medications as described below for the treatment of psoriasis.

Psoriasis is not contagious. A person cannot catch it from someone else, and one cannot pass it to anyone else by skin-to-skin contact. Directly touching someone with psoriasis every day will never transmit the condition.

Many kinds of doctors may treat psoriasis, including dermatologists, family physicians, internal medicine physicians, rheumatologists, and other medical doctors. Dermatologists are doctors who specialize in the diagnosis and treatment of psoriasis, and rheumatologists specialize in the treatment of joint disorders and psoriatic arthritis. Some patients have also seen other allied health professionals such as acupuncturists, holistic practitioners, chiropractors, and nutritionists.

The American Academy of Dermatology and the National Psoriasis Foundation are excellent sources to help find doctors who specialize in this disease. Not all dermatologists and rheumatologists treat psoriasis. The National Psoriasis Foundation has one of the most up-to-date databases of current psoriasis specialists.

Patients with psoriasis are often prone to a variety of other disease conditions, called comorbidities. Cardiovascular disease, diabetes, hypertension, inflammatory bowel disease (IBD), hyperlipidemia, liver problems, and arthritis are more common in patients with psoriasis. All patients with psoriasis need to be carefully monitored by their primary care providers for these associated illnesses. The joint inflammation of psoriatic arthritis and its complications are frequently managed by rheumatologists.

The diagnosis of psoriasis is typically made by obtaining information from the physical examination of the skin, medical history, and relevant family health history.

Sometimes lab tests, including a microscopic examination of tissue obtained from a surgical skin biopsy, may be necessary.

Depending on the extent of skin involvement, psoriasis may be classified into the following three levels:

1. Mild psoriasis: When less than three percent of the body surface area is affected by lesions
2. Moderate psoriasis: When 3 to 10 percent of body surface area is affected
3. Severe psoriasis: When more than 10 percent of body surface area is affected. Erythrodermic psoriasis is a severe and rare type of psoriasis.

There are many effective psoriasis treatment choices. The best treatment is individually determined by the treating doctor and depends, in part, on the type of disease, the severity, the amount of skin involved, and the type of insurance coverage.

For mild disease that involves only small areas of the body (less than 10% of the total skin surface):

• Topical treatments (skin applied), such as creams, lotions, and sprays, may be very effective and safe to use.
• Occasionally, a small local injection of steroids directly into a tough or resistant isolated psoriatic plaque may be helpful.

For moderate to severe psoriasis that involves much larger areas of the body (more than 10% or more of the total skin surface), topical products may not be effective or practical to apply.

• This may require ultraviolet light treatments or systemic (total body treatments such as pills or injections) medicines.
• Internal medications usually have greater risks. Because topical therapy does not affect psoriatic arthritis, systemic medications are generally required to stop the progression to permanent joint destruction.

It is important to keep in mind that as with any medical condition, all medicines carry possible side effects. No medication is 100% effective for everyone, and no medication is 100% safe. The decision to use any medication requires thorough consideration and discussion with your healthcare provider. The risks and potential benefits of medications have to be considered for each type of psoriasis and the individual. Of two patients with precisely the same amount of disease, one may tolerate it with very little treatment, while the other may become incapacitated and require treatment internally.

A strategy to minimize the toxicity of some of these medicines has been commonly called "rotational" therapy.

• The idea is to change the anti-psoriasis drugs every six to 24 months to minimize the toxicity of one medication.
• Depending on the medications selected, this proposal can be an option.
• An exception to this proposal is the use of the newer biological medications as described below.
• An individual who has been using strong topical steroids over large areas of their body for prolonged periods may benefit from stopping the steroids for a while and rotating to a different therapy.

Topical (skin applied) treatments include topical corticosteroids, vitamin D analog creams like calcipotriene (Calcitrene, Dovonex, Sorilux), and topical retinoids (tazarotene [Tazorac]), moisturizers, topical immunomodulators (tacrolimus and pimecrolimus), coal tar, anthralin, and others.

• Topical corticosteroids (steroids, such as hydrocortisone) are beneficial and often the first-line treatment for limited or small areas of psoriasis. These come in many preparations, including sprays, liquids, creams, gels, ointments, and foams. Steroids come in many different strengths, including stronger ones used for elbows, knees, and tougher skin areas and milder ones for areas like the face, underarms, and groin. These are usually applied once or twice a day to affected skin areas. Strong steroid preparations should be limited in use. Overuse or prolonged use may cause problems, including potential permanent skin thinning and damage called atrophy.
• Calcipotriene cream is useful in psoriasis because of its effect on calcium metabolism. The advantage of calcitriol (Vectical) is that it is not known to thin the skin like topical steroids. There is a newer combination preparation of calcipotriene and a topical steroid called Taclonex. Not all patients may respond to calcipotriene. Prolonged use of these types of medications on more than 20% of the skin surface can produce an abnormal rise in body calcium levels.
• Moisturizers, especially with therapeutic concentrations of salicylic acid, lactic acid, urea, and glycolic acid may be helpful in psoriasis. These moisturizers are available in prescription and nonprescription forms. This helps reduce the scales that impede the movement of topical medications into the deeper layers of the skin. Some available preparations include salicylic acid (Salex) and lactic acid (AmLactin, Lac-Hydrin). These may be used one to three times a day on the body. Other bland moisturizers, including Vaseline and Crisco vegetable shortening, may also be helpful in at least reducing the dry appearance of psoriasis.
• Immunomodulators (tacrolimus and pimecrolimus) have also been used with some limited success in mild psoriasis. These have the advantage of not causing skin thinning. They may have other potential side effects, including skin infections and possible malignancies (cancers). The exact association between these immunomodulator creams and cancer is controversial.
• Bath salts or bathing in high-salt-concentration waters like the Dead Sea in the Middle East along with careful exposure to sunlight can be beneficial to psoriasis patients.
• Coal tar is available in multiple preparations, including shampoos, bath solutions, and creams. Coal tar may help reduce the appearance and decrease the flakes in psoriasis. The odor, staining, and overall messiness of coal tar may make it less desirable than other therapies. A major advantage of tar is a lack of skin thinning.
• Anthralin is available topical as a cream, ointment, or paste. The stinging, possible irritation and skin discoloration may make this less acceptable to use. Anthralin may be applied for 10-30 minutes to psoriatic skin.

Coal tar shampoos are very useful in controlling psoriasis of the scalp. Using shampoo daily can be very beneficial adjunctive therapy. There are a variety of over-the-counter shampoos available without a prescription. There is no evidence that one shampoo is superior to another. Generally, the selection of tar shampoo is a matter of personal preference.

Oral medications for psoriasis include methotrexate (Trexall), acitretin (Soriatane), cyclosporine (Neoral), apremilast (Otezla), and others. Oral prednisone (a corticosteroid) is generally not used in psoriasis and may cause a disease flare-up if discontinued.

• Acitretin (Soriatane) is an oral drug used for certain types of psoriasis. It is not effective in all types of diseases. It may be used in people who are not pregnant and not planning to become pregnant for at least three years. The major side effects include dryness of the skin and eyes and temporarily elevated levels of triglycerides and cholesterol (fatty substances) in the blood. Blood tests are generally required before starting this therapy and are needed periodically to monitor triglyceride levels. Patients should not become pregnant while on this drug and usually avoid becoming pregnant for at least three years after stopping this medication.
• Cyclosporine is a potent immunosuppressive drug used for other medical uses, including organ transplantation. It may be used for severe, difficult-to-treat cases of widespread psoriasis. Improvement and results may be very rapid in onset. It may be hard to get someone off of cyclosporine without flaring their psoriasis. Because of the potential cumulative toxicity, cyclosporine should not be used for more than one to two years for most psoriasis patients. Major possible side effects include kidney and blood pressure problems.
• Methotrexate is a common drug used for rheumatoid arthritis, and it has been used effectively for many years in psoriasis. It is usually given in small weekly doses (5 mg-25 mg), either orally or by injection. Blood tests are required before and during therapy. The drug may cause liver and lung damage. Close physician monitoring and monthly to quarterly visits and labs are generally required.
• Apremilast (Otezla) is used to treat psoriasis and psoriatic arthritis, with an entirely novel mode of action (inhibition of an enzyme, phosphodiesterase 4) and does not require intensive laboratory monitoring.

Most patients with psoriasis seem to be overweight. Since there is a predisposition for those patients to develop cardiovascular disease and diabetes, it is suggested strongly they try to maintain normal body weight. Although evidence is sparse, it has been suggested that slender patients are more likely to respond to treatment.

Although dietary studies are notoriously difficult to perform and interpret, it seems likely that an anti-inflammatory diet whose fat content is composed of polyunsaturated oils like olive oil and fish oil is beneficial for psoriasis. The Mediterranean diet is an example Vegetarian and vegan/plant-based diets are also considered anti-inflammatory.

Recently, a new group of drugs called biologics has become available to treat psoriasis and psoriatic arthritis. They are produced by living cell cultures in an industrial setting. They are all proteins and therefore must be administered through the skin because they would otherwise be degraded during digestion. All biologics and biosimilars (drugs close in structure and function to a biologic drug) work by suppressing certain specific portions of the immune-inflammatory response that are overactive in psoriasis.

A convenient method of categorizing these drugs is based on their site of action:

1. Tumor necrosis factor-α (TNF-alpha) inhibitors (certolizumab pegol [Cimzia], etanercept [Enbrel], adalimumab [Humira], infliximab [Remicade, Renflexis], golimumab [Simponi, Simponi Aria])
2. Interleukin 12 and 23 (IL-12/23) inhibitor (ustekinumab [Stelara])
3. Interleukin 17 (IL-17) inhibitors (secukinumab [Cosentyx], brodalumab [Siliq], ixekizumab [Taltz], bimekizumab-bkzx [Bimzelx])
4. Interleukin 23 (IL-23) inhibitor (guselkumab [Tremfya], risankizumab-rzaa [Skyrizi], tildrakizumab [Ilumya])
5. T cell inhibitor abatacept (Orencia)

Drug choice can be complicated, and your physician will help in selecting the best option. In some patients, it may be possible to predict drug efficacy based on a prospective patient's genetics. It appears that the presence of the HLA-Cw6 gene is correlated with a beneficial response to ustekinumab.

Newer drugs are in development and no doubt will be available shortly. As this class of drugs is fairly new, ongoing monitoring and adverse effect reporting continue and long-term safety continues to be monitored. Biologics are all comparatively expensive, especially given the fact that none of them are curative. The FDA has attempted to address this problem by permitting the use of "biosimilar" drugs. These drugs are structurally identical to a specific biological drug and are presumed to produce identical therapeutic responses in human beings to the original, but are produced using a different methodology. Biosimilars are usually available at a fraction of the cost of the original.

Biosimilars currently available include infliximab ( Avsola, Inflectra, Ixifi, Renflexis), etanercept (Erelzi, Eticovo), and adalimumab (Abrilada, Amjevita Cyltezo, Hadlima Hulio, Hyrimoz, Idacio, Yuflyma, Yusimry), and ustekinumab (Wezlana).

Some biologics are administered by self-injections for home use while others are given by intravenous infusions in the doctor's office. Biologics have some screening requirements such as a tuberculosis screening test (TB skin test or PPD test) and other labs before starting therapy. As with any drug, side effects are possible with all biological drugs. Common potential side effects include mild local injection-site reactions (redness and tenderness). There is a concern for serious infections and potential malignancy with nearly all biological drugs. Precautions include patients with known or suspected hepatitis B infection, active tuberculosis, and possibly HIV/AIDS. As a general consideration, these drugs may not be an ideal choice for patients with a history of cancer and patients actively undergoing cancer therapy. In particular, there may be an increased association of lymphoma in patients taking a biologic.

Biologics are expensive medications ranging in price from several to tens of thousands of dollars per year per person. Their use may be limited by availability, cost, and insurance approval. Not all insurance drug plans fully cover these drugs for all conditions. Patients need to check with their insurance and may require a prior authorization request for coverage approval. Some biological manufacturers have patient assistance programs to help with financial issues.

Therefore, the choice of the right medication for your condition depends on many factors, not all of them medical. Additionally, the convenience of receiving the medication and lifestyle affect the choice of the right biologic medication.

Light therapy is also called phototherapy. Several types of medical light therapies include PUVA (an acronym for psoralen + UVA), UVB, and narrow-band UVB. These artificial light sources have been used for decades and generally are available in only certain physician's offices. There are a few companies that may sell light boxes or light bulbs for prescribed home light therapy.

Natural sunlight is also used to treat psoriasis. Daily short, controlled exposures to natural sunlight may help or clear psoriasis in some patients. Skin unaffected by psoriasis and sensitive areas such as the face and hands may need to be protected during sun exposure.

There are also multiple newer light sources like lasers and photodynamic therapy (use of a light-activating medication and a special light source) that have been used to treat psoriasis.

PUVA is a special treatment using a photosensitizing drug and timed artificial light exposure composed of wavelengths of ultraviolet light in the UVA spectrum. The photosensitizing drug in PUVA is called psoralen. Both the psoralen and the UVA light must be administered within one hour of each other for a response to occur. These treatments are usually given in a physician's office two to three times per week. Several weeks of PUVA are usually required before seeing significant results. The light exposure time is gradually increased during each subsequent treatment. Psoralens may be given orally as a pill or topically as a bath or lotion. After a short incubation period, the skin is exposed to a special wavelength of ultraviolet light called UVA. Patients using PUVA are generally sun sensitive and must avoid sun exposure for some time after PUVA. Common side effects of PUVA include burning, aging of the skin, increased brown spots called lentigines, and an increased risk of skin cancer, including melanoma. The relative increase in skin cancer risk with PUVA treatment is controversial. PUVA treatments need to be closely monitored by a physician and discontinued when a maximum number of treatments has been reached.

Narrow-band UVB phototherapy is an artificial light treatment using very limited wavelengths of light. It is frequently given daily or two to three times per week. UVB is also a component of natural sunlight. UVB dosage is based on time and exposure is gradually increased as tolerated. Potential side effects of UVB include skin burning, premature aging, and a possible increased risk of skin cancer. The relative increase in skin cancer risk with UVB treatment needs further study but is probably less than PUVA or traditional UVB.

Sometimes UVB is combined with other treatments such as tar application. Goeckerman is a special psoriasis therapy using this combination. Some centers have used this therapy in a "daycare" type of setting where patients are in the psoriasis treatment clinic all day for several weeks and go home each night.

Recently, a laser (excimer laser XTRAC) has been developed that generates ultraviolet light in the same range as narrow-band ultraviolet light. This light can be beneficial for psoriasis localized to small areas of skin like the palms, soles, and scalp. It is impractical to use in extensive disease.

Psoriasis is not currently curable, but it can go into remission, producing an entirely normal skin surface. Ongoing research is actively making progress in finding better treatments and a possible cure in the future.

Overall, the prognosis for most patients with psoriasis is good. While it is not curable, it is controllable. As described above, recent studies show an association between psoriasis and other medical conditions, including obesity, diabetes, and heart disease.

Complications of psoriasis may include:

• Infections
• Increased risk of heart disease
• Arthritis
• Inflammation of the intestine
• Changes in skin color and texture
• Depression and anxiety

Since psoriasis is inherited, it is impossible at this time to suggest anything likely to prevent its development aside from maintaining a healthy lifestyle.

Psoriasis research is heavily funded and holds great promise for the future. Just the last five to 10 years have produced great improvements in the treatment of the disease with medications aimed at controlling precise sites of the process of inflammation. Ongoing research is needed to decipher the ultimate underlying cause of this disease.

The National Psoriasis Foundation (NPF) is an organization dedicated to helping patients with psoriasis and furthering research in this field. They hold national and local chapter meetings. The NPF website (http://www.psoriasis.org/home/) shares up-to-date reliable medical information and statistics on the condition.

A dermatologist, the American Academy of Dermatology at http://www.AAD.org, and the National Psoriasis Foundation at http://www.psoriasis.org/home/ may be excellent sources of more information.

There are many ongoing clinical trials for psoriasis all over the United States and in the world. Many of these clinical trials are ongoing at academic or university medical centers and are frequently open to patients without cost.

Clinical trials frequently have specific requirements for types and severity of psoriasis that may be enrolled into a specific trial. Patients need to contact these centers and inquire regarding the specific study requirements. Some studies have restrictions on what recent medications have been used for psoriasis, current medication, and overall health. Go to https://clinicaltrials.gov/ to search for any current clinical trials for psoriasis treatments.