Effectiveness of Profiling Serum IL-18 and Neopterin in Diagnosis of Adult-Onset Still’s Disease Complicated by Pulmonary Tuberculosis: A Case Report

Abstract

Adult-onset Still’s Disease (AOSD) is a systemic inflammatory disorder characterized by high fever, skin rashes, and joint pains, and is extremely rare in patients over 80 years of age. An 88-year-old woman was admitted with high fever lasting for > 2 weeks and arthritis of the right knee and bilateral wrists. Further examination revealed that the patient fulfilled the Yamaguchi criteria, the most sensitive and extensively used classification criteria for AOSD. After ruling out other causes and considering a greatly raised serum interleukin-18 (IL-18) level, the patient was diagnosed with AOSD. Before prednisolone therapy, active tuberculosis was excluded using chest computed tomography (CT) and an interferon-gamma release assay (IGRA). After starting the treatment, serum levels of IL-18 and acute-phase reactants were decreased gradually. However, during prednisolone tapering, fever relapsed along with increasing serum acute phase reactant levels. Her serum IL-18 level was decreased but remained at a high level, and the neopterin level was further increased. These findings suggested the onset of another disease, but not AOSD recurrence. A chest CT scan revealed new lung infiltrates. Despite the initial negative IGRA result, cultures and polymerase chain reaction tests of bronchoalveolar lavage and sputum were positive for Mycobacterium tuberculosis. She was placed on a 9-month course of anti-tuberculosis therapy and continued prednisolone tapering. She showed steady improvement and her cytokine profile showed a decrease in the IL-18 and neopterin levels. In conclusion, cytokine profiling is useful in making the diagnosis of AOSD and subsequent pulmonary tuberculosis developed during steroid therapy.