Abstract: 【Abstract】 Objective To analyze clinical characteristics of ketosis-associated prurigo pigmentosa after ketogenic diet and bariatric surgery. Methods Clinical data were collected from patients with ketosis-associated prurigo pigmentosa, who were diagnosed and treated in Department of Dermatology, Peking University People′s Hospital from September 2018 to September 2020. The clinical characteristics, sequelae and therapeutic effect of dietary modification were analyzed and summarized. Results A total of 6 patients with ketosis-associated prurigo pigmentosa were collected, including 5 females who developed prurigo pigmentosa after ketogenic diet, and 1 male who developed prurigo pigmentosa after bariatric surgery. The skin lesions mainly involved the chest, back, waist and abdomen, and rarely involved the eyelids, axillae, elbows and mons pubis. Common skin lesions included urticaria-like erythema, papules and pigmentation arranged in a reticular distribution, and rare skin lesions included mung bean- to soybean-sized blisters, whose walls were liable to break. Among 5 patients undergoing routine urine analysis, 4 were positive （from + to ++++） for ketone bodies in the urine, and 3 were positive for urinary protein （+）. Pathological examination in 2 patients showed epidermal spongiosis, scattered necrotic keratinocytes, basal cell liquefaction, lymphocyte infiltration in the superficial dermis, and erythrocyte extravasation. The 6 patients were advised to eat staple foods. After dietary modification, 5 patients were nearly cured within 1 week; 1 patient, who continued ketogenic diet for weight loss, still received marked improvement after the treatment with minocycline at a dose of 100 mg/d in spite of restriction of carbohydrate intake. The levels of urinary ketone bodies and urinary protein in the 6 patients all returned to normal within 1 week after treatment. Conclusions Ketosis plays an important role in the occurrence of prurigo pigmentosa. Dietary modification alone or adjuvant medical treatment such as minocycline is effective for the treatment of ketosis-related prurigo pigmentosa.

Key words: Prurigo, Ketogenic diet, Bariatric surgery, Prurigo pigmentosa, Dietary modification