Advances in Psoriasis Research and Side-by-Side Treatment Review

New Insights, Treatment Updates and Comparisons

Naveed Saleh, MD, MS; Reviewed by Graeme Lipper, MD


May 31, 2017


The medical community has been familiar with psoriasis for over 2000 years. Hippocrates, who lived between 460 and 377 BC, described what appears to be psoriasis in the Hippocratic Corpus. Specifically, Hippocrates used the term psora ("itch") to describe the condition.[1]

Although psoriasis has been treated for eons, understanding of the disease has rapidly grown in recent years. Thanks to new research, the medical community is starting to appreciate the systemic effects of the disease, an association that links cardiovascular disease, metabolic disorder, and other conditions to psoriasis.

Psoriasis is a papulosquamous disorder that manifests in red, raised lesions with silvery scales. This condition is autoimmune, chronic, and inflammatory.[2] It affects more than 6.7 million American adults, or more than 3.1% of the American population.[3] Worldwide, psoriasis affects 2% of the population.[4] Additionally, psoriasis seems to affect men and women in equal numbers, and although adults are more likely to have psoriasis, it can appear at any age.[3,5]

Psoriasis is truly a biopsychosocial condition. In addition to affecting the skin, psoriasis can cause problems with the joints (psoriatic arthritis) and cardiovascular system. It can result in physical disability and interfere with activities of daily living, and is also a psychiatric stressor.[6] Specifically, patients with psoriasis have a higher prevalence of alcoholism and depression.

Despite the lack of a cure, there are effective treatments, including topical treatments, systemic (oral and parenteral) treatments, and light therapy.[3]

Psoriasis is an immune-mediated condition. Specifically, T cells are activated and travel to the skin where they release cytokines. These cytokines cause vascular and epidermal hyperproliferation and proinflammatory effects.[6]

About 80% of people who have psoriasis have mild to moderate disease. The remaining 20% have moderate to severe disease.[7] Psoriatic plaques most commonly affect body surfaces exposed to chronic friction and trauma, a response known as the Koebner phenomenon, first described by Heinrich Koebner in 1876.[8]

Psoriasis takes on many forms and can present in a variety of ways:

  • Plaque psoriasis (also called psoriasis vulgaris) is the most common form of psoriasis, representing about 90% of cases. It involves plaques or red, raised lesions with silvery scales. These plaques tend to enlarge slowly over time. Plaque psoriasis usually presents in a symmetrical fashion and most commonly affects the elbows, knees, scalp, lower back, and buttocks, especially the intergluteal cleft.[3,4,9]

  • Guttate psoriasis involves smaller, drop-shaped skin lesions that appear on the scalp, limbs, and trunk. This type of psoriasis is usually triggered by an upper respiratory infection, most commonly group A Streptococcus.[3,9]

  • Inverse psoriasis affects the intertriginous areas of the armpits, genitals, and breasts.[3,9]

  • Pustular psoriasis involves pus-filled blisters and is triggered by medications, infections, and stress. Of note, because psoriasis is an autoimmune disease, the pus is noninfectious.[3,9]

  • Erythrodermic psoriasis can be quite serious and requires immediate medical attention. This psoriasis is widespread and can be triggered by sunburn, corticosteroids, or other medications. Furthermore, poorly controlled, long-term psoriasis can trigger this more severe iteration.[3,9]

Sometimes a person can have more than one type of psoriasis. Additionally, one type of psoriasis can transmute to another.[3,9]