Autoimmune diseases can be tricky to diagnose because they often share similar symptoms. For example, psoriasis and lupus are two types of autoimmune diseases that can cause skin symptoms. About two-thirds of people with lupus experience some type of skin condition. Sometimes, the skin and joint symptoms of lupus can look like psoriasis, and psoriasis symptoms may look like lupus.

To make sure you get the proper treatment, be aware of the skin symptoms that each of these conditions causes so you can differentiate between the two.

Who Gets Psoriasis vs. Lupus?

Psoriasis is more common than lupus in the United States. According to an article in JAMA Dermatology, more than 7.5 million adults in the U.S. have been diagnosed with psoriasis, while about 1.5 million people in the U.S. have lupus. Of those diagnosed with lupus, about 10 percent have a type of lupus that is limited to the skin, known as cutaneous lupus erythematosus.

Both psoriasis and lupus affect people of different genders, races, and ethnicities. Although psoriasis is equally common in men and women, about 90 percent of individuals with lupus are women, according to the Lupus Foundation of America. However, cutaneous lupus is more common in men.

Psoriasis is most common in non-Hispanic white individuals. In contrast, lupus is less prevalent (total number of cases in a population at a given time) in white women compared to African American, Hispanic, Native American, Asian American, Native Hawaiian, and Pacific Islander women.

Psoriasis and lupus can develop at any age. People are most often diagnosed with psoriasis between 20 and 30 years of age or between the ages of 50 and 60. Lupus is usually diagnosed from ages 15 to 44.

If you have a family member with either psoriasis or lupus, you may be more likely to develop the disease.

One study found that psoriasis and psoriatic arthritis (arthritis that affects the joints) were more common in people with lupus than in the general population. Additionally, the incidence (rate of new cases) of lupus-associated rashes was higher in those also diagnosed with psoriasis.

What Causes Psoriasis and Lupus?

Scientists don’t know the exact reason why some people develop psoriasis or lupus, but both are caused by the immune system attacking its own tissues. If your immune system attacks your skin cells in either disease, you may see a skin rash.

In psoriasis, white blood cells called T cells become overactive and are primarily responsible for causing inflammation in the skin and joints. In lupus, inflammation involves many different immune cells, including T cells, B cells, and neutrophils that can attack multiple organs.

What Does Psoriasis Look Like?

Psoriasis can appear on any part of the body. Psoriasis symptoms can appear in unique ways in different people, but common symptoms include patches of thick, dry, scaly skin that can look red, brown, or purple, depending on your skin tone. These patches are also often covered in a silvery coating called scale.

The type of psoriasis also affects how psoriasis looks, and there are five main types:

• Plaque psoriasis is the most common type of psoriasis. This type looks like red or purple patches of thick, scaly skin that can appear anywhere on the body.
• Guttate psoriasis appears as small, round spots of inflammation that are red or darker than the surrounding skin. It can appear on any part of the body — commonly the arms, legs, chest, or back — and is associated with a preceding infection, especially strep throat.
• Inverse psoriasis appears as a red or darker patch of smooth, irritated skin in the skin folds such as the underarms, breasts, genital area, or buttocks.
• Pustular psoriasis looks like small, pus-filled bumps commonly occurring on the hands or feet.
• Erythrodermic psoriasis is a rare and life-threatening type of psoriasis involving large areas of red or discolored skin along with pain, fever, dehydration, and changes in heart rate.

Beyond Skin: Nail and Joint Psoriasis

Psoriasis can affect more than your skin — it can also affect your nails and your joints. Psoriasis can also affect nails, a condition known as nail psoriasis. This can cause the nails to thicken, change color, and develop pits or ridges. In severe cases, the nail can even separate from the nail bed or fall off entirely. Psoriatic arthritis can cause joint pain, swelling, and stiffness, which can affect one or more joints in the body, including the fingers, toes, spine, and pelvis. In addition to joint symptoms, psoriatic arthritis can also cause fatigue, eye inflammation, and changes to the nails, such as pitting, thickening, or separation from the nail bed.

What Does Lupus Look Like?

Lupus can affect the skin on any part of the body. Lupus rashes are most common in areas of the skin that can be exposed to the sun, such as the face, arms, legs, and shoulders. Many of the symptoms of lupus and psoriasis are similar. It’s also possible to have both psoriasis and lupus at the same time.

Lupus rashes are classified based on three types of cutaneous lupus: acute cutaneous lupus (ACL), subacute cutaneous lupus erythematosus (SCLE), and chronic cutaneous lupus.

Acute Cutaneous Lupus

Symptoms of ACL can appear when your lupus is active.

A malar rash is the most recognizable sign of lupus. This is a butterfly-shaped rash that appears on the face, stretching across the nose and cheeks. However, it usually doesn’t affect other parts of the face, such as the area between your lips and nose (nasolabial folds). If you have a malar rash, you may look like you’re blushing in mild cases. In severe cases, it can be very red and itchy.

If the rash appears on other parts of the body, such as the arms or legs, it’s called a maculopapular rash of lupus or photosensitive lupus dermatitis. It may look like an allergic reaction.

Malar rashes usually come and go, and do not tend to lead to scarring or discoloration. They are often triggered by sun exposure and are often accompanied by other symptoms, such as joint pain.

Subacute Cutaneous Lupus Erythematosus

SCLE can occur anywhere on the body but usually occurs in areas that are exposed to the sun, such as the neck, arms, shoulders, and legs.

The rash that occurs with SCLE may look very similar to plaque psoriasis, with areas of scaly, red, or darker skin with distinct edges, but does not have the silvery scale. An SCLE rash can also form in a ring-shaped pattern with darker borders and a lighter center. Although this type of rash may look like psoriasis, it typically does not itch as psoriasis rashes tend to. It also usually does not leave a scar but may result in patches of lighter skin when it clears.

Chronic Cutaneous Lupus

Chronic cutaneous lupus is also known as discoid lupus due to the shape of the rash.

Discoid lupus usually appears as coin-shaped, thick, scaly patches of skin that are red or darker in color. Lesions commonly appear on the face, scalp, or ears but can be anywhere on the body.

Discoid lupus lesions can also look like psoriasis. However, they usually aren’t itchy or painful. Discoid lesions on the scalp may cause hair loss. Without treatment, these patches can stay on the skin for years. People with a darker skin tone may notice that when discoid lupus clears, a discolored patch that is either darker or lighter than the surrounding skin is left behind.

Other Lupus Symptoms

In addition to causing similar skin symptoms, both lupus and psoriasis can lead to joint pain and arthritis.

A MyPsoriasisTeam member shared, “I have had psoriasis for three years and was diagnosed with lupus 10 months ago. It is very difficult for me, as I am a very active person normally. These conditions seem to be targeting the tendons in my shoulder, hands, hips, and feet the most.”

Lupus can also affect your nails in a similar way to psoriasis, causing them to become discolored or to crack or fall off.

Diagnosing Lupus and Psoriasis

A doctor specializing in treating skin diseases — called a dermatologist — will help to tell the difference between psoriasis and lupus by performing a physical exam, drawing blood, and getting your medical history.

An antinuclear antibody (ANA) test can help diagnose autoimmune disorders. Although the ANA test result can sometimes be positive in people with psoriasis, almost everyone diagnosed with lupus will have a positive ANA test result because it is a very sensitive test.

Your doctor may also take a small sample of skin (a skin biopsy) and look at it under a microscope. This type of test can help distinguish which condition is causing the rash.

Lupus and Psoriasis Treatment

Many of the treatment options for psoriasis and cutaneous lupus are similar. Topical medications applied to the skin can treat a rash caused by psoriasis or lupus. Creams, ointments, or lotions with anti-inflammatory medications — such as a corticosteroid — can improve symptoms of the rash.

Oral medications and biologics may also be used to decrease inflammation all over the body for both conditions. Biologics are medications made from living cells to treat a variety of medical conditions. Keep in mind, though, biologics that work well for one condition may not work for the other. Some medications that can work for both conditions include:

• Methotrexate (Trexall)
• Ustekinumab (Stelara)
• Tumor necrosis factor-alpha (TNF-alpha) inhibitors

Although some medications can be used for either psoriasis or lupus, certain treatments may trigger the other condition. For example, the antimalarial medication hydroxychloroquine (Plaquenil) that’s used to treat lupus may trigger new psoriasis symptoms or make existing symptoms worse. Phototherapy can treat psoriasis symptoms but can often trigger cutaneous lupus flare-ups due to photosensitivity (the skin becomes unusually sensitive to sunlight or other sources of ultraviolet light).

Whether you’re dealing with psoriasis, lupus, or any other condition that causes skin changes, you’ll want to keep an eye out for any unusual symptoms and talk to your doctor right away. Remember, an accurate diagnosis is key to effective treatment, and your doctor can work with you to develop a plan to manage your condition and improve your quality of life. Take charge of your health and work with your health care team to find the best path forward.

Talk With Others Who Understand

MyPsoriasisTeam is the social network for people with psoriasis and their loved ones. On MyPsoriasisTeam, more than 116,000 members come together to ask questions, give advice, and share their stories with others who understand life with psoriasis.

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