Lupus eritematoso sistémico con factor antinuclear (fan) negativo: un reto diagnóstico

Abstract

Systemic lupus erythematosus (SLE) is an autoimmune disease affecting 20 to 150 people per 100,000 population, characterized by the production of autoantibodies, the main antibodies involved in the pathophysiology of this disease, being the antinuclear antibodies known as antinuclear factor (ANF). Positive FAN is now considered an entry criterion for the classification of FAN-negative patients, which poses a diagnostic challenge for those with negative FAN, a clinical entity described since 1976 with a prevalence of 2-20%. Despite advances in FAN identification techniques, there are several patient factors such as age, disease activity, glucocorticoid use, proteinuria, infection and/or sepsis, that lead to antibody negativity at diagnosis; as well as different technical factors when processing FAN by indirect immunofluorescence (IFI). This review addresses SLE classification criteria, FAN identification techniques, causes of negativity, and other diagnostic methods for those patients with negative antinuclear antibodies and clinical SLE, with the aim of providing information to health care professionals that will enable the timely diagnosis and treatment of patients with this pathology, thus improving their prognosis and quality of life.