Psoriasis in Child
Psoriasis is fairly common in childhood but may also occur in infancy (see infantile psoriasis). It occurs worldwide and is estimated to affect 1%-2% of the population, with 20% of cases presenting before 20 years of age.
Several clinical patterns exist, and multiple forms may be observed in a single patient. Typical plaque-type psoriasis (psoriasis vulgaris) is discussed here; other forms include guttate psoriasis (which often follows streptococcal pharyngitis), palmar-plantar psoriasis, erythrodermic psoriasis, and pustular psoriasis. Inverse psoriasis occurs in intertriginous or thin-skinned areas of the body, such as the axillae, groin, genitals, submammary area, face, and eyelids.
Pediatric psoriasis often presents as red, scaly plaques on the face. Psoriasis can also be limited to the nails or to body areas such as the genitals, scalp, feet, or even a solitary fingertip. Fingernails are more often involved compared to toenails in children. A review of pediatric psoriasis found that scalp psoriasis was more common in girls, while nail involvement was more common in boys, suggesting a possible role of chronic incidental trauma in these locations.
Approximately 8% of patients develop psoriatic arthritis. Those with nail involvement seem to be at increased risk for developing this erosive seronegative arthritis, which can be a source of considerable morbidity. Warning signs of psoriatic arthritis include tender, swollen joints that may be warm to the touch or painful swelling of the fingers.
Comorbidities may include obesity, hyperlipidemia, diabetes mellitus, Crohn disease, ulcerative colitis, rheumatologic disease, juvenile idiopathic arthropathy, depression, anxiety, bipolar disorder, substance abuse, and eating disorders.
The National Psoriasis Foundation is an excellent resource for patients: www.psoriasis.org.
L40.0 – Psoriasis vulgaris
9014002 – Psoriasis
- The scale of seborrheic dermatitis is yellowish and greasy, as opposed to the silvery, dry scale of psoriasis. Lesions are also ill-defined, unlike the well-defined plaques of psoriasis. Seborrheic dermatitis often involves the eyebrows and perinasal cheeks. Sebopsoriasis is a term for the clinical overlap of psoriasis of the face, scalp, and ears and seborrheic dermatitis.
- Whereas psoriasis usually involves the extensor surfaces of knees and elbows, the lichenified pruritic plaques of chronic atopic dermatitis typically involve the flexor surfaces of the extremities.
- Tinea corporis can be easily differentiated from psoriasis by the demonstration of hyphal elements on potassium hydroxide (KOH) preparation.
- The pink, often-truncal papules of viral exanthem typically lack significant scale and may coalesce into larger plaques.
- Pityriasis rosea may easily be confused with guttate psoriasis. The presence of a larger herald patch and the orientation of plaques along skin tension lines of the trunk are helpful clues to diagnose pityriasis rosea. Lesions of pityriasis rosea typically have a trailing-edge scale with a collarette of scale along the lateral portions of the lesions while psoriasiform scale occurs diffusely along the lesion.
- Pityriasis rubra pilaris presents as large coalescing orange-red plaques with prominent foci of uninvolved skin (islands of sparing).
- Lichen planus presents with pruritic violaceous papules with overlying white reticulated markings (Wickham striae), most often involving the wrists and ankles.
- Crusted scabies should be considered, especially in immunocompromised or institutionalized patients.
- Mycosis fungoides is rare in children and tends to present with atrophic scaly patches involving sun-protected sites.
- Caspase recruitment domain family member 14 gene (CARD14)-associated papulosquamous eruption refers to a distinctive phenotype with overlapping features of psoriasis and familial pityriasis rubra pilaris (PRP). The patients typically present early in life and report a family history of psoriasis or PRP. The cheeks, chin, and ears are typically affected. This disease is difficult to treat using conventional therapies, while treatment with ustekinumab appears to be effective.
- The differential for nail psoriasis includes trauma, trachyonychia, pitting associated with alopecia areata or atopic dermatitis, and acute or chronic paronychia.