An Overview of Psoriatic Disease

Psoriatic disease is an autoimmune disease that includes two specific inflammatory conditions. These two conditions, psoriasis and psoriatic arthritis (PsA), are a result of an overactive immune system. Psoriasis and PsA primarily affect the joints and skin throughout the body.

Types

Up to 30% of people who have psoriasis eventually develop psoriatic arthritis, according to the National Psoriasis Foundation. It is also possible to have PsA and develop psoriasis later on, but these cases are much rarer.

Psoriasis

Psoriasis is known for causing a rapid build-up of skin cells characterized by skin patches, called plaques. Some people have localized patches while others have complete body coverage. 

There are five main types of psoriasis.

• Plaque psoriasis
• Guttate psoriasis
• Inverse psoriasis
• Pustular psoriasis
• Erythrodermic psoriasis

Of the five, plaque psoriasis affects up to 90% of the people with psoriasis. As a whole, psoriasis affects 3.1% of Americans. There is no cure for this lifelong disease, but various treatments can control symptoms and reduce excessive skin growth.

Psoriatic Arthritis  

PsA causes chronic inflammation of the joints in the places where tendons and ligaments connect to bone. The inflammatory process eventually leads to pain, swelling, and stiffness in the joints. Anyone can get PsA but new diagnoses are usually seen during middle age (ages 30 to 50). For most people with PsA, their symptoms start years after psoriasis begins. 

Much like psoriasis, there is no cure for PsA.  But the growing number of treatments can halt the disease’s progression, reduce pain and other symptoms, and preserve joints and range of motion. Early diagnosis and treatment are vital because delayed treatment even in a short period can result in permanent joint damage.

Symptoms

Inflammation is the main symptom of psoriatic disease. 

Psoriasis

Dry, thick, and raised skin patches are the most common signs of psoriasis. Psoriasis causes other signs and symptoms which are dependent on:

• Type of psoriasis
• Places where patches and other symptoms appear
• Amount of psoriasis covering the body

Plaque psoriasis causes plaques of different sizes. Sometimes, these plaques are small and form together to create larger plaques. They usually appear on the scalp, elbows, knees, and low back, but can appear anywhere on the body. It is common for these plaques to be itchy, but dermatologists will advise you to not scratch patches, because this will cause them to thicken. They can also bleed and crack.

Guttate psoriasis causes tiny bumps to appear on the skin suddenly. Bumps often cover the torso, legs, and arms, but they can also appear on the face, scalp, and ears. Bumps are salmon or pink colored, small, and scaly. They may clear without treatment. When they do clear, they usually do not return. In these cases, guttate psoriasis is temporary, but it possible to have the condition for life, for it to clear and come back later in life, and for plaque psoriasis to result after a guttate outbreak. There is no way to predict what will happen after the first outbreak clears.

Inverse psoriasis develops in areas where skin folds. Symptoms of inverse psoriasis may include:

• Smooth, red patches of skin
• A silvery-white coating on patches
• Sore and painful skin

Pustular psoriasis causes pus-filled bumps to appear on the hands and feet. The pus contains white blood cells. Bumps are not infectious, but they can be painful and affect activities of the hands and feet, such as typing and walking.

Erythrodermic psoriasis can be life-threatening and requires immediate medical care. It only affects 3% of people with psoriasis. Symptoms may include:

• Burnt-looking skin on most of the body
• Chills and fever
• Muscle weakness
• Rapid pulse
• Severe itch
• Problems keeping warm  
• Shedding skin                

People who develop erythrodermic psoriasis usually have another type of psoriasis that is severe and does not improve despite aggressive treatment. Anyone who noticing symptoms of psoriasis that are worsening should talk to their healthcare provider so as to avoid complications. 

Psoriatic Arthritis

Most people have skin symptoms for years before they experience joint pain. When joint symptoms start to develop, they will be subtle at first and may include:

• Swollen and tender joints, especially in the fingers
• Heel pain
• Swelling on the backs of the legs, above the heel
• Morning stiffness that fades with activity and as the day progresses

PsA symptoms may develop slowly and be mild or they can come on suddenly and become severe. PsA is progressive which means if not treated successfully, it will worsen with time.

Symptoms of PsA that develop with time include:

• Fatigue
• Tenderness, pain and swelling over tendons
• Swollen fingers and toes that may resemble sausages
• Stiffness, pain, throbbing, and tenderness in multiple joints
• Reduced range of motion
• Nail changes, including nail separation from the nail bed and pitting (small pits on the surface of the nails)
• Spine stiffness, pain and torso movement problems
• Eye inflammation, a condition called uveitis

Symptom Severity

While there is a connection between the severity of psoriasis and the development of PsA, there is no connection between the severity of psoriasis and the severity of PsA. This means having severe skin symptoms does not mean joint symptoms will be severe, and having many joints affected by PsA does not mean your skin will be covered in lesions. Furthermore, the same body parts are not necessarily affected. For example, if PsA affects your finger joints, psoriasis may not.

Flare-Ups

Anyone who has psoriatic disease knows the condition waxes and wanes, so you will have periods of flare-ups and periods of remission. 

Many different things trigger flare-ups, including

• Stress
• Skin trauma, including cuts, scrapes, and tattoos
• Dry skin
• Sunburn
• Certain medications
• Climate
• Alcohol consumption
• Cigarette smoke
• Gluten
• Infections 

Remission

Remission is a period of little or no disease activity. Some people with psoriasis can have spontaneous remission, where symptoms clear up without treatment. PsA remission is not as common, especially when a person has both PsA and psoriasis.  

People with milder forms of PsA and those who are treated early on may have a higher chance of achieving remission. In fact, research reported in Arthritis & Therapy finds up to 60% of people with PsA were able to achieve remission after one year of treatment with biologic medications. While remission is realistic and achievable, it depends on when a person starts treating and how aggressive psoriatic disease symptoms are. 

Research reported in the British Medical Journal finds up to 75% of people who achieve remission will have a recurrence within six months of stopping medication. There are few people who can experience drug-free remission with PsA and even with continued treatment, symptoms are likely to return.

Causes and Risk Factors

True causes for psoriatic disease are unknown. But researchers believe genetics and the environment play a role in the development of psoriasis and PsA.

Psoriasis

While psoriasis and PsA have similar causes, the processes that cause them to manifest themselves are not so similar. 

Genetics: One out of every three people with psoriasis reports having a relative with the condition, this according to the National Psoriasis Foundation. Children have a 10% chance of developing the condition if one parent has psoriasis, and if two parents have psoriasis, a child’s risk increases to 50%.

Immune System: When the immune system is overactive in people with psoriasis, inflammation is created inside the body, which results in the symptoms seen on the skin. Healthy skin cells are produced too quickly and get pushed to the surface. Normally, it would take a month for skin cells to go through a healthy cycle, but in people with psoriasis, the process takes days. The body cannot shed skin cells that fast and plaques build up.

Infection: While psoriasis is not contagious, it may also be triggered by an infection, specifically the infection that causes strep throat.

Comorbidities: When a person has two or more conditions, these are called comorbidities. Comorbidities that increase the risk for psoriasis include PsA, heart disease, metabolic syndrome, and other autoimmune conditions, such as Crohn’s disease.

Skin trauma: Any skin trauma, such as a cut or sunburn, can cause psoriasis lesions to develop. Even tattoos can trigger psoriasis because they cause skin trauma. This response is called the Koebner phenomenon.

Psoriasis is also worse in patients who are overweight and in smokers.

Psoriatic Arthritis

Much like psoriasis, PsA is an autoimmune disorder where the body’s immune system attacks its own healthy tissues and cells. This autoimmune response causes joint pain and inflammation.

The highest risk factors for developing PsA are:

Psoriasis: Having psoriasis is the leading cause of developing PsA. 

Genes: There is a genetic link to PsA, as most people with PsA report having a sibling or parent with the condition.

Age: While anyone of any age can develop PsA, the disease’s onset is between the ages of 30 and 50.

Infection: Researchers believe PsA may result when an infection triggers the immune system.  

Trauma: Physical trauma can increase the risk of PsA in people who already have psoriasis. One study from the European League Against Rheumatism (EULAR) found the risk for PsA increases by 50% among people with psoriasis when they are exposed to physical trauma, especially when trauma is deep in the bones or joints.

Diagnosis

Even though psoriasis and PsA are often seen together, they are not always diagnosed at the same time. Symptoms of psoriasis are often seen years before joint pain and inflammation because joint symptoms are less obvious. Of course, in rare cases, joint symptoms may occur prior to skin symptoms, which may make diagnosis more difficult or result in misdiagnosis. 

Psoriasis

There are no specific diagnostic tests for psoriasis. A diagnosis is usually made by examining skin lesions. Because psoriasis can resemble other skin conditions, including eczema, your healthcare provider may want to confirm the diagnosis with a biopsy, taking an affected skin sample and examining it under a microscope. Psoriasis is will appear thicker than eczema and other skin conditions.

Your healthcare provider will also ask about family history. It is likely you have a first-degree relative with the condition. Your healthcare provider may also try to pinpoint triggers for skin symptoms, including new medications or recent stressful events.

Psoriatic Arthritis

There is no single test to confirm a PsA diagnosis. To diagnose PsA, your healthcare provider will perform a physical exam and request imaging and lab tests. He or she will also want to rule out other conditions that cause similar symptoms, such as rheumatoid arthritis and gout.

A physical exam will include:

• Checking joints for swelling and tenderness, especially in the fingers, toes, and spine
• Checking fingernails for pitting, flaking, and other visible abnormalities
• Pressing the soles of your feet and around the heels to look for swelling and tenderness

Imaging will include plain x-rays to pinpoint joint changes specific to PsA and magnetic resonance imaging (MRI) to provide detailed images of the hands and soft tissues throughout the body. MRI can also check for problems in ligaments and tendons of the feet and low back.

Lab testing may include blood work to rule out other conditions. For example, a rheumatoid factor blood test used to diagnose rheumatoid arthritis can rule out PsA.

Treatment

Treatments for people with psoriatic disease include disease modifying anti-rheumatic drugs (DMARDs) and biologics.

DMARDs may relieve more severe symptoms of psoriatic disease and attempt to slow down or halt joint and tissue damage and disease progression. DMARDs, such as Arava (leflunomide), Trexall (methotrexate) and antimalarial drugs, i.e. Plaquenil (hydroxychloroquine), can suppress the immune system and halt inflammation. The most common side effects of DMARDs include skin rash, temporary hair loss, weight loss, liver damage, and gastrointestinal symptoms, including nausea and abdominal pain.

Biologics include drugs that block a substance called tumor necrosis factor (TNF), which is known for causing inflammation. These medications are expensive, and healthcare providers will only prescribe them when other treatments have not worked. Biologics used to treat psoriatic disease include Enbrel (etanercept), Humira (adalimumab), Orencia (abatacept), Remicade (infliximab), and Simponi (golimumab). Side effects may bruising at the include site, increased susceptibility to infection, diarrhea, and nausea. Biologics used to treat psoriasis now also extend beyond TNF inhibitors.

Your healthcare provider can also prescribe treatments that focus on one condition or the other. For example, topical medications can treat skin symptoms while non-steroidal anti-inflammatory drugs (NSAIDs) can ease pain and inflammation.  

A Word From Verywell

Living with psoriatic disease can be stressful so it is important to take the steps necessary to manage symptoms and maintain your quality of life. And while there is no cure for psoriatic disease, researchers continue to study the complex relationship between the immune system and psoriatic disease in the quest to develop new therapies to put a stop to inflammation and abnormal immune system responses. In the meantime, the disease is treatable and manageable. In addition to taking your medications, it is important to practice a healthy lifestyle, which includes a balanced diet, not smoking, stress management, and avoiding trauma to your skin, joints and bones.