Chronic Prurigo Associated With Allergic Contact Dermatitis: A Case Series Highlighting Textile Dyes and Fragrance Allergens.

Abstract

Background: Chronic prurigo (CP) is a condition characterised by chronic pruritus and pruriginous lesions. While frequently associated with atopic dermatitis (AD), its link with allergic contact dermatitis (ACD) is less understood.

Objectives: To describe the clinical features, diagnostic findings, and therapeutic outcomes of CP associated with ACD.

Patients/materials/methods: This case series included patients diagnosed with CP or prurigo nodularis, identified through medical records from a specialised ACD clinic. Inclusion criteria were positive patch tests identifying relevant allergens, complete medical histories, and resolution or improvement of CP lesions after allergen avoidance. Patch testing was performed using the Spanish Extended Baseline Series and additional allergen panels as needed, following International Contact Dermatitis Research Group guidelines.

Results: Six patients were identified: four cases of CP associated with fragrances and two with textile dyes. All patients improved significantly with allergen avoidance; two required dupilumab. Histological findings and clinical responses suggested a Th2-driven immune response in fragrance-induced ACD and a Th2/Th17 involvement in azo dye-related cases.

Conclusions: ACD caused by textile dyes and fragrances may manifest as papular dermatitis with features consistent with CP. Patch testing should be considered for idiopathic CP or cases associated with AD. Further studies are needed to clarify the immune mechanisms underlying this association.