The many variants of psoriasis
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.
PRACTICE RECOMMENDATIONS
› 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
Lichen planus usually appears slightly more purple than psoriasis and typically involves the mouth, flexural surfaces of the wrists, genitals, and ankles.
Other conditions in the differential include pityriasis lichenoides chronica, which may be identified on skin biopsy. Inverse psoriasis can be difficult to differentiate from candida intertrigo, erythrasma, or tinea cruris.
A potassium hydroxide (KOH) preparation can help differentiate psoriasis from candida or tinea. In psoriasis, a KOH test will be negative for fungal elements. Mycology culture on skin scrapings may be performed to rule out fungal infection. Erythrasma may exhibit a coral red appearance under Wood lamp examination.
If a lesion fails to respond to appropriate treatment, a careful drug history and biopsy can help clarify the diagnosis.
Document disease
It’s important to thoroughly document the extent and severity of the psoriasis and to monitor the impact of treatment. The Psoriasis Area and Severity Index is a commonly used method that calculates a score based on the area (extent) of involvement surrounding 4 major anatomical regions (head, upper extremities, trunk, and lower extremities), as well as the degree of erythema, induration, and scaling of lesions. The average redness, thickness, and scaling are graded on a scale of 0 to 4 and the extent of involvement is calculated to form a total numerical score ranging from 0 (no disease) to 72 (maximal disease).
Continue to: Many options in the treatment arsenal
