Psoriasis 101

What role does the immune system play in psoriasis?

Dr. Hawkes: The immune system is essential for the development of psoriasis and associated comorbidities. Immune cells that produce tumor necrosis factor, interferon, interleukin (IL)-17, IL-23, and IL-36 appear to be the primary pro-inflammatory signals that drive psoriasis.

Once the immune system in a susceptible individual becomes stimulated, it creates a persistent, overactive immune response that results in increased inflammation in the skin, blood, and other organs. This self-amplifying immune response is difficult to shut off without a medical intervention and leads to several negative health consequences when undertreated or ignored. If you dampen the immune system in certain ways, you also mute psoriasis.

What is the most common form of psoriasis, and is there an area of the body most affected?

Dr. Hawkes: Plaque psoriasis represents the most common disease variant and is seen in 80 to 85% of affected patients. This form is often seen on the trunk, elbows, knees, umbilicus (navel), scalp, ears, hands, and feet. Approximately one-third of patients may present with psoriatic arthritis, which may present as joint pain, redness, swelling, a swollen digit, nail changes, or uveitis (eye inflammation).

That said, if you focus too much on plaque psoriasis or the characteristic body areas, then you will certainly miss more subtle or less common forms of disease. Less common variants of psoriasis include inverse (skin folds like eyelids, neck, armpits, and genitals), guttate (sudden, smaller psoriasis plaques that frequently follow a streptococcal pharyngitis), erythrodermic and pustular (diffuse redness of more than 75% of the body, usually with scattered skin peeling and pus-filled bumps), or palmoplantar disease (psoriasis limited to the palms and soles).

What are the main treatment options?

Dr. Hawkes: For mild or limited disease without psoriatic arthritis, topical steroids and other anti-inflammatory or nonsteroidal topical medications are the mainstay treatment of psoriasis.

For more extensive or bothersome disease with or without psoriatic arthritis, we rely on a variety of treatments including phototherapy, oral medications that alter the increased immune response (such as methotrexate, cyclosporine, or apremilast), and injectable medications known as biologics. We now have an incredible selection of highly effective, safe biologic medications to choose from when treating psoriasis patients. The use of a single biologic or systemic medication is often enough to manage psoriasis in an individual, though more extensive or difficult cases such as those with psoriatic arthritis may require the use of multiple treatments (combination therapy) to control their psoriatic disease.

Other lifestyle modifications are also important in the management of psoriasis, such as weight loss, a healthy diet, exercise, tobacco cessation, reduced alcohol intake, and stress- or anxiety-reducing practices.

What is the biggest misconception about psoriasis?

Dr. Hawkes: The most common misconception I encounter is the idea that psoriatic disease is restricted to the skin or is primarily the result of an external factor such as gluten-containing foods or laundry detergents. These two ideas over-look or underestimate the complex immunopathogenesis of psoriasis, its systemic effects beyond the skin, and its associated link with our genes and immune system.

Despite the many dietary modifications tried or extensive undertakings to purge their environment of potential psoriasis-causing factors, patients are left with their relentless, chronic disease at the end of the day. I am able to work with these newly diagnosed patients to help them redirect their efforts and begin to focus on the aspects of their systemic disease that we can manage using evidence-based treatments and lifestyle modifications.