Prurigo Pigmentosa Induced by the Ketogenic Diet

Abstract

Prurigo pigmentosa, also called Nagashima disease or "keto-rash", is a rare inflammatory skin condition. The etiology is unknown, but conditions associated with ketosis (fasting, diabetes, postbariatric surgery) often accompany this rash. Clinical case: A 13-year-old patient with no significant pathological history, overweight, on a ketogenic diet, was consulted for maculopapular skin lesions and erythematous plaques, discretely pruritic, persistent, confluent, with centrifugal extension, located at the posterior cervical, axillary, later thoracic, epigastric and lumbar regions. Hematological, biochemical, and immunological investigations were normal. Initial therapy with medium potency topical corticosteroid and anti-H1 antihistamine was ineffective, instead, under treatment with doxycycline and giving up the ketogenic diet, the resolution of the lesions was obtained, residual hyperpigmentation with a reticulated pattern persisting. Conclusions: We present this case to highlight the increasingly common association between prurigo pigmentosa and the ketogenic diet. Dermatologists should identify the relationship between the timing of rash onset and resolution in relation to diet, with a view to early diagnosis and treatment with optimal patient outcomes.