Prurigo pigmentosa post-bariatric surgery: a case report.

Background: Prurigo pigmentosa (PP), also referred to as Nagashima disease, is an acquired dermatological condition that is characterized by pruritic erythematous eruptions including papules and plaques surrounded by a reticular pattern of hyperpigmentation. It was first described in 1971 when Japanese dermatologist Masaji Nagashima noticed similar dermatological manifestations among 8 patients of Asian descent. The disease has been strongly associated with ketosis and ketogenic diet; however, the underlying etiology is unknown. Effective treatment involves an oral antibiotic and a balanced diet. The disease classically affects young women of Asian descent, but cases affecting males and people of non-Asian ancestry have also been observed. We present an unusual case of PP in a Saudi male that started 18 days following bariatric surgery. Case Description: The patient is a 25-year-old morbidly obese Saudi male who complained of an intensely pruritic rash 3 weeks after undergoing bariatric surgery. His past medical history is positive for irritable bowel syndrome (IBS). A punch skin biopsy yielded the diagnosis, and a combination treatment consisting of minocycline and a topical corticosteroid was prescribed. The patient presented again 2 weeks after the initial visit with complete resolution of the rash. He reported adherence to the medication regimen. Pruritus had resolved. Upon examination, post-inflammatory hyperpigmentation in a reticular pattern was observed over the trunk, upper abdomen, and chest. Hydroquinone 4% cream was prescribed to treat the post-inflammatory hyperpigmentation. Conclusions: Nowadays, PP cases are being reported from all around the world, including cases of PP that appeared following bariatric surgery for weight loss without ketogenic dietary modification. Theoretically, the typical PP patient is a young adult female from Eastern Asia who has been adherent to a ketogenic diet. In contrast, we report a case of a Saudi male who did no dietary modifications, but underwent bariatric surgery. Treatment with minocycline resulted in successful complete resolution.