Overlapping rheumatoid arthritis and antisynthetase syndrome with secondary Sjögren’s syndrome: a case report and review of the literature

BACKGROUND: Overlap syndromes account for about 25% of autoimmune diseases. They are many possible combinations of known autoimmune diseases increasingly diagnosed with the identification of of a large number of autoantibodies. In this case report, we present a patient with rare overlapping rheumatoid arthritis–antisynthetase syndrome with associated secondary Sjögren’s syndrome atypically presenting without interstitial lung disease. CASE PRESENTATION: A 52-year-old Sinhalese female, a known patient with type 2 diabetes mellitus, presented with a history of symmetrical inflammatory-type polyarthritis with significant morning stiffness, proximal muscle weakness, pain, and roughening of the fingertips with associated sicca symptoms of 5 months duration. Examination revealed features of active joint inflammation, mechanic’s hand, xerostomia, and left-sided breast lump. Investigations confirmed the presence of rheumatoid arthritis with strongly positive rheumatoid factor (202 U/ml) and anti-cyclic citrullinated peptide antibody (717 U/ml). Antisynthetase syndrome was also diagnosed with borderline-positive anti-aminoacyl-tRNA antibodies but without interstitial lung disease. Sjögren’s syndrome was confirmed by the clinical history and histology and considered a secondary disorder. As her breast lump proved to be benign, no further interventions were done. She was started on sulfasalazine and methotrexate with steroid bridging therapy and achieved remission and had good control of the disease without any joint deformity or flare-up on 6-month clinic follow-up. DISCUSSION: Overlapping rheumatoid arthritis–antisynthetase syndrome is a very rare disease with disabling complications. Early identification of the atypical presentations of the overlap syndromes, by thorough investigations, helps physicians to prescribe proper disease-modifying antirheumatoid drugs and biological drugs. It also helps predict the prognosis of the patients before they develop complications.