Pearly Scale

Specialty: Skin.

• micaceous peeling
• silver scales
• pearly peeling plaques

Why it occurs

• Vulgaris or plaque psoriasis (accelerated epidermal hyperproliferation due to a chronic inflammatory state mediated by cytokines IL-23 and IL-17, with a keratinocyte cycle shortened from 28 to only 4 days)
• Gutty or guttate psoriasis (small scaly eruptive lesions triggered by streptococcal infection)
• Palmoplantar keratodermas of genetic or acquired origin
• Hypertrophic lichen planus (hyperkeratotic plaques of purplish tint with adherent peeling)
• Severe seborrheic dermatitis of the scalp (coarse pearly false scaling).

Initial workup

Careful physical examination looking for signs of Brocq's methodical scratching (spark plug stain sign, Duncan-Dulck film, and Auspitz bleeding dew). Punch biopsy of the plaque confirmed paratofitis, regular psoriasiform acanthosis, absence of granular layer and presence of Munro-Sabouraud microabscesses filled with neutrophils in the stratum corneum.

Standard management

• Calcipotriol cream 0.005% — vitamin D analogue that inhibits proliferation and promotes normal differentiation of keratinocytes
• Clobetasol propionate 0.05% ointment — very high potency corticosteroid used in short periods to reduce basal inflammation
• 5% salicylic acid in Vaseline — keratolytic agent designed to soften and remove thick, pearly scales to allow penetration of other active drugs
• Methotrexate (systemic treatment of choice in extensive cases of cutaneous psoriasis with or without joint involvement, doses of 15 to 25 mg weekly orally or subcutaneously, with folic acid supplementation).