Prurigo pigmentosa from contact allergy to chrome in detergent.

Prurigo pigmentosa is a recurrent inflammatory dermatosis characterized by pruritic erythematous papules and reticulate hyperpigmentation that occurs most frequently in spring and summer. The etiology of prurigo pigmentosa remains unknown. Numerous authors have suggested that various contact allergens may be pathogenic or triggering factors, but nearly all attempts to identify an allergen have been unsuccessful. We report a case of prurigo pigmentosa induced by contact allergy to chrome in detergent, supporting the conclusion that contact allergens such as chrome may play a rôle in inducing prurigo pigmentosa.