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
Drug-provoked psoriasis is divided into 2 groups: drug-induced and drug-aggravated. Drug-induced psoriasis will improve after discontinuation of the causative drug and tends to occur in patients without a personal or family history of psoriasis. Drug-aggravated psoriasis continues to progress after the discontinuation of the offending drug and is more often seen in patients with a history of psoriasis.14 Drugs that most commonly provoke psoriasis are beta-blockers, lithium, and antimalarials.10 Other potentially aggravating agents include antibiotics, digoxin, and nonsteroidal anti-inflammatory drugs.10
Consider these skin disorders in the differential diagnosis
The diagnosis of psoriasis is usually clinical, and a skin biopsy is rarely needed. However, a range of other skin disorders should be kept in mind when considering the differential diagnosis.
Mycosis fungoides is a type of cutaneous T-cell lymphoma that forms erythematous plaques that may show wrinkling and epidermal atrophy in sun-protected sites. Onset usually occurs among the elderly.
Pityriasis rubra pilaris is characterized by salmon-colored patches that may have small areas of normal skin (“islands of sparing”), hyperkeratotic follicular papules, and hyperkeratosis of the palms and soles.
Seborrheic dermatitis, dandruff of the skin, usually involves the scalp and nasolabial areas and the T-zone of the face.
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