PSORIASIS

June 14, 2021

Psoriasis is a multisystem inflammatory disease with predominantly skin and joint involvement. It has a bimodal age of onset (16 to 22 and 57 to 60 years) and affects both sexes equally. Pathogenesis is multifactorial, involving dysregulated inflammation and genetic associations. Beyond the physical dimensions of disease, psoriasis has an extensive emotional and psychosocial effect on patients; it can result in stigmatization, poor self-esteem, and increased stress, affecting social functioning and interpersonal relationships.

The diagnosis of psoriasis is primarily clinical. There are different clinical types of psoriasis (Table 1),1 the most common of which is chronic plaque psoriasis, affecting 80% to 90% of patients with psoriasis. The hallmark of classic plaque psoriasis is well-demarcated, symmetric, and erythematous plaques with overlying silvery scale (Figure 1). Plaques are typically located on the scalp, trunk, buttocks, and extremities but can occur anywhere on the body. Patients might demonstrate nail involvement, which can present without concomitant plaques (Figure 2). Active lesions might be itchy or painful. Psoriasis can also present as an isomorphic response, where new lesions develop on previously normal skin that has sustained trauma or injury. The severity of disease can be helpful in guiding management and is classified as mild, moderate, and severe.

Table 1.

Clinical manifestations of psoriasis

CLINICAL MANIFESTATION	CLINICAL FINDINGS
Plaque psoriasis	Well circumscribed, erythematous, scaly plaques > 0.5 cm in diameter, either as single lesions or as generalized disease Classified further according to anatomic sites
• Flexural	Also known as intertriginous or inverse psoriasis Well circumscribed, minimally scaly, thin plaques localized to the skin folds (inframammary, axillary, groin, genital, natal cleft regions)
• Nail	Can present without concomitant skin plaques Pitting, distal onycholysis, subungual hyperkeratosis, oil drop sign, splinter hemorrhages, leukonychia, crumbling, red lunula Nail involvement is a predictor of psoriatic arthritis
• Scalp	One of the most common sites of psoriasis Often difficult to treat
• Palmoplantar	Localized to the hands and soles of feet Confluent redness and scaling without obvious plaques to poorly defined scaly or fissured areas to large plaques covering the palm or sole
Other variants
• Guttate	Acute eruption of “dew-drop,” salmon-pink, fine-scaled, small papules on the trunk or limbs Can follow history of group A streptococcal pharyngitis or perianal group A streptococcus dermatitis
• Pustular	Sheets of monomorphic pustules on painful, inflamed skin Most commonly localized to the palms or soles
• Erythroderma	Acute or subacute onset of generalized erythema covering 90% or more of the patient’s entire body with little scaling Might be associated with hypothermia, hypoalbuminemia, electrolyte imbalances, and high-output cardiac failure Life-threatening emergency
• Annular	Well demarcated erythematous scaly plaques with central clearing

Data from the Canadian Psoriasis Guidelines Committee.

Topical therapy is the standard of care for treatment of mild to moderate disease. A large proportion of patients would benefit from topical therapy, which can be initiated at the primary care level. If topical agents do not elicit an adequate response or if they are not practical owing to the affected body surface area, these patients can be referred for assessment by a dermatologist, at which point systemic therapy with topical adjuncts might be more suitable. Presence of psoriatic arthritis might also call for systemic therapies in collaboration with a rheumatologist.

Reference:

Kim WB, Jerome D, Yeung J. Diagnosis and management of psoriasis. Can Fam Physician. 2017;63(4):278-285.

PSORIASIS

Table 1.

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