prurigo

Prurigo is a group of chronic pruritic skin disorders characterized by scratch-induced lesions. The term encompasses several clinically distinct entities, most notably papular prurigo (prurigo simplex) and prurigo nodularis. Papular prurigo, often called papular prurigo of childhood, presents with multiple small, firm, intensely itchy papules on exposed surfaces such as the arms and legs and often resolves over weeks to months. Prurigo nodularis typically affects adults and features clusters of firm, hyperkeratotic nodules, 1–2 cm in diameter, on the forearms, legs, trunk, or buttocks; itch is usually severe and persistent, with thickened, leathery skin (lichenification).

Pathophysiology is not completely understood but is dominated by an itch-scratch cycle with possible neural and inflammatory contributions. Associations include atopy, xerosis (dry skin), and, in some cases, systemic disease or medications. The diagnosis is clinical; biopsy is reserved for atypical cases and may show features of chronic dermatitis such as epidermal hyperkeratosis, acanthosis, and dermal inflammation.

Management focuses on breaking the itch–scratch cycle and addressing any underlying condition. General measures include regular emollients and strategies to reduce scratching. Topical therapies such as corticosteroids, calcineurin inhibitors, and intralesional steroids for nodules are commonly used. Phototherapy (narrowband UVB) can be effective for some patients. Systemic options include oral antihistamines (often sedating at night), gabapentinoids (gabapentin, pregabalin), doxepin, and mirtazapine. For refractory disease, immunosuppressants such as methotrexate may be considered. Emerging biologics, notably dupilumab, have shown benefit in prurigo nodularis. Treatment is individualized and may involve management of coexisting skin or systemic conditions. Prognosis varies: papular prurigo in children often resolves, while prurigo nodularis tends to be longer-lasting with remissions and relapses.