title: Erythema nodosum leprosum: reactional leprosy.
abstract: The different clinical forms of leprosy are mainly related to the variety of immunological responses to the infection. Thus, lepromatous leprosy occurs in patients with a poor cell-mediated immunity to Mycobacterium leprae, whereas tuberculoid leprosy is associated with a high resistance to leprosy bacillus. Intermediate forms, including borderline tuberculoid leprosy, borderline lepromatous leprosy, and borderline leprosy, are a continuous and unstable spectrum of the disease. Leprosy reactions are rare and not well-known states that interrupt the usual chronic course and clinical stability of patients with leprosy. They are expressions of immunological perturbations. Attending to the clinical and histopathological manifestations, leprosy reactions may be separated in 2 or 3 different variants: reverse reaction (type I), erythema nodosum leprosum (type II), erythema polymorphous (type II) and Lucio's phenomenon, mainly considered a type II reaction, but sometimes designated type III. Type I leprosy reaction, also named "upgrading reaction," occurs in borderline leprosy states and is associated with a shift toward the tuberculoid pole. Type II reaction usually occurs in lepromatous leprosy, and there are 3 different clinical variants, including erythema nudosum leprosum, erythema polymorphous-like reaction, and Lucio's phenomenon.
authors.affiliation: Department of Pathology, Hospital General Universitario, Guadalajara, Spain. jcuevas@sescam.org
authors.forename: Jesús
authors.initials: J
authors.lastname: Cuevas
authors.forename: José Luis
authors.initials: JL
authors.lastname: Rodríguez-Peralto
authors.forename: Rosario
authors.initials: R
authors.lastname: Carrillo
authors.forename: Félix
authors.initials: F
authors.lastname: Contreras
mesh_terms: D003937:Diagnosis, Differential; D004893:Erythema Nodosum / Q000175:diagnosis* / Q000188:drug therapy / Q000473:pathology; D006801:Humans; D015440:Leprosy, Lepromatous / Q000175:diagnosis* / Q000188:drug therapy / Q000473:pathology