Adult-onset Still’s disease and Muckle-Wells syndrome - two sides of the same coin?

Abstract

Introduction. Adult-onset Still?s disease (AOSD), a systemic inflammatory disorder, often represents a heterogeneous entity and diagnosis requires the exclusion of mimicking disorders, including autoinflammatory diseases. We present a patient who meets the diagnostic criteria for AOSD and Muckle?Wells syndrome (MWS). Case outline. A 35-year-old male presented with lymphadenopathy and a chronic nonspecific rash, fever spikes, widespread arthralgia, and joint effusions. Laboratory results showed increased inflammation, leukocytosis, neutrophilia, thrombocytosis, and elevated liver enzymes, accompanied by negative immunoserological tests. Patient was diagnosed with AOSD and prednisone (15 mg/d), methotrexate (10 mg/w) and chloroquine (250 mg/d) are introduced in therapy. Due to refractory course, patient was introduced with anti IL-6 biological agent tocilizumab in 2014 (8 mg/kg monthly). However, after three doses, the drug is stopped due to disease exacerbation. In 2015, there was suspicion that there was another underlying disease from the autoinflammatory spectrum, but DNA analysis of the most common mutations in the NLRP3 gene was negative. In 2017, an ear, nose, and throat specialist confirmed bilateral sensorineural hearing loss, and in 2019, amyloidosis was confirmed after biopsy of the duodenum. Patient fulfilled a new-proposed diagnostic criteria for MWS and confirmation of mutation in NLRP3 gene is not obligatory according to Eurofever registry. Conclusion. The symptoms of AOSD and MWS partly overlap, as well as their diagnostic criteria. In chronic refractory cases of AOSD, evaluation of diagnosis should be performed and autoinflammatory syndromes must be kept in mind.