Applied Evidence

The many variants of psoriasis

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Erythema, skin thickening, and scales typify most cases, but other patterns exist. Tx choices may differ, depending on how much body surface area is covered.


› Consider guttate psoriasis if small (often < 1 cm) pink scaly papules appear suddenly, particularly in a child who has an upper respiratory tract infection. C

› Document extent of disease using a tool such as the Psoriasis Area and Severity Index, which calculates a score based on the area (extent) of involvement surrounding 4 major anatomical regions. C

› Consider prescribing UV light treatment or a combination of alcitretin and topical corticosteroid if > 10% of the body surface area is involved but joints are not affected. C

Strength of recommendation (SOR)

A Good-quality patient-oriented evidence
B Inconsistent or limited-quality patient-oriented evidence
C Consensus, usual practice, opinion, disease-oriented evidence, case series



The “heartbreak of psoriasis,” coined by an advertiser in the 1960s, conveyed the notion that this disease was a cosmetic disorder mainly limited to skin involvement. John Updike’s article in the September 1985 issue of The New Yorker, “At War With My Skin,” detailed Mr. Updike’s feelings of isolation and stress related to his condition, helping to reframe the popular concept of psoriasis.1 Updike’s eloquent account describing his struggles to find effective treatment increased public awareness about psoriasis, which in fact affects other body systems as well.

The overall prevalence of psoriasis is 1.5% to 3.1% in the United States and United Kingdom.2,3 More than 6.5 million adults in the United States > 20 years of age are affected.3 The most commonly affected demographic group is non-­Hispanic Caucasians.

Our expanding knowledge of pathogenesis

Studies of genetic linkage have identified genes and single nucleotide polymorphisms associated with psoriasis.4 The interaction between environmental triggers and the innate and adaptive immune systems leads to keratinocyte hyperproliferation. Tumor necrosis factor (TNF), interleukin (IL) 23, and IL-17 are important cytokines associated with psoriatic inflammation.4 There are common pathways of inflammation in both psoriasis and cardiovascular disease resulting in oxidative stress and endothelial cell dysfunction.4 Ninety percent of early-onset psoriasis is associated with human leukocyte antigen (HLA)-Cw6.4 And alterations in the microbiome of the skin may contribute, as reduced microbial diversity has been found in psoriatic lesions.5

Comorbidities are common

Psoriasis is an independent risk factor for diabetes and major adverse cardiovascular events.6 Hypertension, dyslipidemia, inflammatory bowel disease, nonalcoholic fatty liver disease, chronic kidney disease, and lymphoma (particularly cutaneous T-cell lymphoma) are also associated with psoriasis.6 Psoriatic arthritis is frequently encountered with cutaneous psoriasis; however, it is often not recognized until late in the disease course.

There also appears to be an association among psoriasis, dietary factors, and celiac disease.7-9 Positive testing for IgA anti-endomysial antibodies and IgA tissue transglutaminase antibodies should prompt consideration of starting a gluten-free diet, which has been shown to improve psoriatic lesions.9 In addition to its impact on physical health, cutaneous psoriasis often affects mental health. Increased anxiety, depression, and sleep disorders are commonly encountered, revealing the far-reaching effects of psoriasis. The persistent associated itch of psoriasis is often distressing and negatively impacts the patient’s quality of life.

The different types of psoriasis

The classic presentation of psoriasis involves stubborn plaques with silvery scale on extensor surfaces such as the elbows and knees. The severity of the disease corresponds with the amount of body surface area affected. While plaque-type psoriasis is the most common form, other patterns exist. Individuals may exhibit 1 dominant pattern or multiple psoriatic variants simultaneously. Most types of psoriasis have 3 characteristic features: erythema, skin thickening, and scales.

Certain history and physical clues can aid in diagnosing psoriasis; these include the Koebner phenomenon, the Auspitz sign, and the Woronoff ring. The Koebner phenomenon refers to the development of psoriatic lesions in an area of trauma (FIGURE 1), frequently resulting in a linear streak-like appearance. The Auspitz sign describes the pinpoint bleeding that may be encountered with the removal of a psoriatic plaque. The Woronoff ring is a pale blanching ring that may surround a psoriatic lesion.

Psoriasis appearing on traumatized tissue

Continue to: Chronic plaque-type psoriasis


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