▶Papulosquamous (ie, elevated lesions with scale) condition with a tendency to persist or recur for years.
▶Characterized by inflammation and hyperproliferation of the epidermis.
▶Likely results from a genetic predisposition (family history often is positive) and an environmental trigger (eg, infection, trauma).
▶Recent literature links psoriasis to other systemic comorbidities, in particular a higher prevalence of metabolic syndrome (ie, obesity, dyslipidemia, hypertension, and elevated blood glucose) and cardiovascular disease in children and adults. Psoriasis may occur in some children with juvenile idiopathic arthritis (JIA). Typically, this occurs within 2 years of diagnosis of JIA.
▶Appearance of lesions
■Lesions are well-defined papules and plaques that are pink to deep red and have an adherent white to silvery “micaceous” scale (Figure 52.1).
– Removal of scale produces bleeding points (Auspitz sign) (Figure 52.2).
– Scale may be absent or less prominent in occluded areas (eg, diaper area, axillae) (Figure 52.3).
■Variants
– Infantile psoriasis: may appear as generalized erythroderma or as sharply demarcated erythema (with minimal scale) in diaper region (Figure 52.4), axillae, and umbilicus.
–Guttate psoriasis: Often precipitated by pharyngeal or perianal Streptococcus pyogenes infection; begins as generalized erythematous macules and papules (that may mimic a viral exanthem); later, characteristic scale appears (Figure 52.5).
– Pustular psoriasis: small pustules studded over the surface of deep red plaques.
– Inverse psoriasis: lesions located predominantly in the axillae and groin.
▶Distribution
■Scalp (scaling and erythema) (Figure 52.6), posterior auricular, elbows, knees, umbilicus, and gluteal cleft; however, any body region may be affected.
■Lesions appear in areas of trauma (ie, Koebner phenomenon), explaining involvement of the extensor surfaces of the extremities.
■Nail involvement is common, consisting of pitting or thickening and yellowing.
Look-alikes
Disorder | Differentiating Features |
Lichen planus | •Purple, polygonal papules and small plaques. •Fine scale (not thick adherent scale) is present. •Oral involvement common, with thin, white, elevated linear lesions forming a lacy, reticulated appearance. |
•Patients may exhibit muscle weakness. •Characteristic cutaneous findings include heliotrope rash and Gottron papules (ie, erythematous papules located over the dorsal surfaces of interphalangeal joints of the fingers). | |
•May be confused with guttate psoriasis. •Small, thin oval plaques with long axes parallel to lines of skin tension. •Lesions covered by thin, fine ”trailing scale” (lags behind advancing red border, and free edge of scale points inward toward center of plaque). | |
•May be difficult to distinguish from psoriasis when only the scalp and face are involved. •Typical lesions have greasy scale. •Auspitz sign absent. •In infants, seborrheic dermatitis and psoriasis may be indistinguishable. |
▶The diagnosis is made clinically based on the appearance and distribution of lesions.
▶Observation of Auspitz sign strongly suggests a diagnosis of psoriasis.
▶Therapy is directed at reducing inflammation and normalizing epidermal proliferation.
▶Topical therapy (first line): Treatment often employs more than one agent.
■Mid-potency (or, occasionally, high-potency) topical glucocorticoids (often used in conjunction with calcipotriene)
■Calcipotriene: normalizes epidermal proliferation; may be used as monotherapy or in conjunction with topical corticosteroids; may cause hypercalcemia in infants or small children who may require large surface area application
■Others: anthralin or liquor carbonis detergens (tar derivatives) and topical retinoids occasionally used
▶Phototherapy or photochemotherapy: UV-B or UV-A therapy (alone or combined with psoralen, when known as PUVA) may be used for patients with severe disease who fail topical therapy.
▶Systemic therapy: Methotrexate, cyclosporine A, or acitretin may be used for patients with severe disease who fail topical therapy. Biologic agents (that target TNF-α, IL-12, IL-17, or IL-23) occasionally are used, but very few of these agents are approved for use in children.
Treating Associated Conditions
▶When guttate psoriasis is suspected, test for pharyngeal (or perianal if the physical examination is suggestive) S pyogenes infection and treat if infection is confirmed.
▶For patients with significant disease, consult with or refer to a pediatric dermatologist to optimize therapy.
▶Refer patients in whom the diagnosis is uncertain, those who do not respond to appropriate therapy, or those who develop pustular disease.
▶American Academy of Dermatology: Psoriasis resource center.
https://www.aad.org/public/diseases/scaly-skin/psoriasis
▶MedlinePlus: Information for patients and families (in English and Spanish) sponsored by the US National Library of Medicine and National Institutes of Health.
https://www.nlm.nih.gov/medlineplus/ency/article/000434.htm
▶National Psoriasis Foundation: Provides extensive information (English and Spanish) about the disease and its treatment.
▶Society for Pediatric Dermatology: Patient handout on psoriasis.
https://pedsderm.net/for-patients-families/patient-handouts/#Psoriasis