Prurigo Pigmentosa – an increasingly diagnosed dermatological condition associated with ketogenic diet

Prurigo pigmentosa (PP) is a rare inflammatory dermatosis, clinically characterized by intensely pruritic, erythematous papules and papulovesicles, with reticular hyperpigmentation upon healing. We herein report four cases in adults of different ethnic backgrounds, in which the disease was associated with ketogenic metabolic states due to fasting or carbohydrate-restricted diets. In all cases, treatment with doxycycline led to rapid clearance of all skin lesions. The findings highlight the importance of a thorough dietary history to avoid misdiagnosis and to initiate targeted therapy. Due to changing dietary trends, this dermatosis should be considered in patients with altered eating behavior and recent appearance of PP-suspicious skin lesions.