Sjögren's syndrome with adult-onset Still's disease: an overlap syndrome?

Adult-onset Still's disease (AOSD) is a rare systemic auto-inflammatory disease that is an exclusive diagnosis that needs to previously exclude infections, tumors, and rheumatic diseases. There are few reports on AOSD overlapping with other rheumatic diseases. We reported a 55-year-old male who presented with a high, daily spiking fever associated with an evanescent salmon-pink rash, arthralgia, and sore throat. He had a history of dryness of the mouth and eyes for decades with no medical treatment. On admission, tests for antinuclear antibody (ANA) and anti-SSA/Ro-52 antibody were positive, and salivary gland biopsy showed focal lymphocytic sialadenitis with a focus score of ≥ 1 foci/4 mm2, which was consistent with a diagnosis of primary Sjögren's syndrome (SS). However, the disease activity of SS was low at the time of the report. Combined with significantly elevated acute phase reactants, the patient also met the classification criteria of both Yamakuchi and Futel for AOSD. His clinical symptoms were relieved quickly with glucocorticoid therapy. We also reviewed the literature on SS with AOSD and AOSD with other rheumatic diseases, and scattered case reports were retrieved. So we think that AOSD is not an absolutely exclusive diagnosis and can occur in patients with other rheumatic diseases. To our knowledge, this is the only literature review of a reported AOSD case in a SS patient.