01812nas a2200241   4500000000100000008004100001260001200042653002400054653002200078653002400100653002500124653002500149653001500174100001400189700001100203700001400214700001300228700001400241245010000255490000700355520119400362022001401556       2026                            d  c04/202610afenômeno de Lúcio10aLepra lepromatosa10alepromatous leprosy10aLucio’s phenomenon10aMycobacterium leprae10aVasculitis1 aScafati J1 aPena C1 aRamallo C1 aMoavro D1 aGarcía M00aLepromatous reaction mimicking a primary systemic vasculitis: Case report and literature review0 v223 a<p>Lucio's phenomenon is a rare necrotizing skin reaction, almost exclusive to diffuse lepromatous leprosy, that can mimic systemic vasculitis and lead to diagnostic and therapeutic errors. We report the case of a 32-year-old woman from Paraguay with prolonged fever, hepatomegaly, and violaceous, painless necrotic skin lesions on her limbs. She was initially treated with corticosteroids for presumed vasculitis without clinical improvement. Physical examination revealed madarosis, lepromas, and altered thermal-pain sensitivity. Skin biopsy showed a perivascular histiocytic infiltrate with acid-fast bacilli, confirming multibacillary lepromatous leprosy. Treatment with rifampicin, dapsone, and clofazimine was initiated, resulting in good clinical evolution. Lucio's phenomenon is an immune-mediated vasculopathy that may produce false-positive serologies and mimic autoimmune diseases. Histopathological confirmation is essential to avoid unnecessary immunosuppressive therapy. It should be considered in the differential diagnosis of necrotic skin ulcers, especially in patients from endemic regions. Early recognition and specific treatment help prevent severe complications.</p>  a2173-5743