Enfermedad de Still Del Adulto y Síndrome de Schnitzler: ¿formas distintas del mismo espectro de enfermedad? Un caso de urticaria y fiebre recurrente en el anciano

Adult-onset Still’s disease (AOSD) and Schnitzler syndrome (SchS) are rare, not fully understood, multisystemic and autoinflammatory disorders, with a challenging differential diagnosis. The authors report the case of an elderly man with unexplained fever, arthralgia, weight loss, spleen enlargement, lymphadenopathy, anemia, hyperferritinemia and IgG monoclonal gammopathy. Autoimmunity, infection, haematological disease and malignancy were excluded. The clinical spectrum fulfilled both AOSD diagnostic criteria and IgG-variant SchS Strasbourg criteria. Symptom resolution was achieved with immunosuppressive therapy, supporting the diagnosis of an autoinflammatory disorder, a diagnostic challenge for the medical team emerging as an unexpected cause of fever in the elderly.