Psoriasis

Psoriasis is a chronic, immune-driven skin disease in which the skin makes new cells too fast, producing raised, scaly patches. It runs in families (NHS). It usually starts in adolescence or adulthood, but it is probably under-recognised in infants and toddlers. There it is easily mistaken for Atopic Dermatitis, because childhood plaques are thinner, less scaly and more often on the face than adult plaques (Siegfried & Hebert 2015; Napolitano 2022). About 5% of children have overlapping features of both conditions, called psoriasis-eczema overlap (Napolitano 2022). These children have flexural eczema plus psoriatic plaques without thick scale, and they itch more than children with psoriasis alone (Siegfried & Hebert 2015).

Psoriasis [part-of] Differential Diagnosis of Toddler Eczema Psoriasis [relates] Atopic Dermatitis

Telling it apart from eczema in a toddler. Psoriasis forms sharply demarcated, pink-red, thicker plaques. Eczema forms poorly defined patches with fine dry scale (Napolitano 2022). The distribution differs. Psoriasis favours the nappy area and gluteal cleft, the scalp, behind the ears, the umbilicus and the extensor surfaces. Toddler AD typically spares the nappy area and settles into the elbow and knee creases from age 1–2 (Türe Avcı 2026; Healio). The most common childhood form is inverse (flexural) psoriasis. It is often confused with Nappy Rash and should be suspected when a nappy rash is sharply edged and keeps returning despite good care (Napolitano 2022; DermNet). Other clues include fine nail pits and a “thumb sign” plaque on a sucked thumb (the Koebner effect, where plaques form at sites of minor injury). A strep throat can trigger a sudden shower of small drop-like plaques (guttate psoriasis) (Siegfried & Hebert 2015; NHS). Itch is usually mild to moderate, compared with the severe itch of AD (Napolitano 2022; Healio). On brown and black skin the plaques can look grey and leave dark marks (Post-Inflammatory Hyperpigmentation) after they clear (NHS).

Psoriasis [relates] Nappy Rash Psoriasis [relates] Seborrhoeic Dermatitis Psoriasis [causes] Post-Inflammatory Hyperpigmentation

Why the distinction matters and what happens next. There are agreed diagnostic criteria for AD but none for childhood psoriasis, and biopsy is rarely practical in a toddler. Diagnosis is therefore clinical, and psoriasis should be considered when “eczema” responds poorly to standard treatment (Napolitano 2022; Türe Avcı 2026). Only about a third of affected children have a family history (Siegfried & Hebert 2015). The first steps of treatment overlap with eczema care: Emollient Therapy and Topical Corticosteroids. Psoriasis-eczema overlap also responds to psoriasis-style treatment including steroids (Siegfried & Hebert 2015). Psoriasis-specific options such as vitamin D creams and coal tar, and phototherapy or systemic medicines for severe disease, are specialist decisions in under-5s (NHS). A toddler with suspected psoriasis should be assessed by a GP and, if uncertain, referred (When to Refer).

Emollient Therapy [treats] Psoriasis Topical Corticosteroids [treats] Psoriasis

Connections

• Differential Diagnosis of Toddler Eczema — inflammatory mimic, source: Türe Avcı 2026; Napolitano 2022
• Nappy Rash — napkin psoriasis: persistent sharply edged fold plaques, source: DermNet Napkin dermatitis
• Atopic Dermatitis — ~5% paediatric overlap; distinguished by edge, site and itch, source: Napolitano 2022; Siegfried & Hebert 2015
• Seborrhoeic Dermatitis — both involve nappy/folds and are less itchy than AD, source: Healio
• When to Refer — treatment-resistant “eczema” warrants review, source: Napolitano 2022
• Tapinarof Cream — first licensed for adult plaque psoriasis (2022), source: FDA VTAMA label