Lucio's phenomenon is a rare and aggressive necrotising variant of erythema nodosum leprosum that classically occur in patients with undiagnosed, diffuse non-nodular lepromatous leprosy. It is a potentially fatal leprosy reaction characterised by extensive, bizarrely-shaped, painful purpuric skin lesions and ulcerations. Lucio's phenomenon is very rarely reported outside of Mexico and Costa Rica.