Know All About: Psoriasis

Psoriasis is a chronic, multisystem inflammatory disease with predominantly skin and joint involvement. Beyond the physical dimensions of disease, psoriasis has an extensive emotional and psychosocial effect on patients, affecting social functioning and interpersonal relationships. As a disease of systemic inflammation, psoriasis is associated with multiple comorbidities, including cardiovascular disease and malignancy. The diagnosis is primarily clinical and a skin biopsy is seldom required. Depending on the severity of disease, appropriate treatment can be initiated. For mild to moderate disease, first-line treatment involves topical therapies including corticosteroids, vitamin D3 analogues, and combination products. These topical treatments are efficacious and can be safely initiated and prescribed by primary care physicians. Patients with more severe and refractory symptoms might require further evaluation by a dermatologist for systemic therapy.

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
• 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

 

Measures of disease severity

SEVERITY	MEASURES*
Mild	< 3% BSA† Disease with a minimal effect on the patient’s QoL; patient can achieve an acceptable level of symptomatic control by routine skin care measures and topical therapy
Moderate	3% to 10% BSA Disease that cannot be, or would not be expected to be, controlled to an acceptable degree by routine skin care measures or disease that substantially affects the patient’s QoL, either because of the extent of the disease, physical discomfort (pain or pruritus), or location (eg, the face, hands, feet, or genitals)
Severe	> 10% BSA Disease that cannot be, or would not be expected to be, satisfactorily controlled by topical therapy and that causes severe degradation of the patient’s QoL

BSA—body surface area, QoL—quality of life.

^*These are definitions for clinical practice, as applied in the Canadian guideline. The Psoriasis Area and Severity Index is another measure of disease severity, based on BSA, erythema, induration, and scaling.

The size of a single hand is estimated to be 1% BSA.