Co-occurrence of spondyloarthropathy and connective tissue disease: development of Sjögren's syndrome and mixed connective tissue disease (MCTD) in a patient with ankylosing spondylitis.

Spondylarthropathies (SpA) and connective tissue diseases (CTD) are clinically distinct entities which, at first glance, seem to have little in common. However, a link between SpA and CTD has recently been suggested by a study in which a higher prevalence of Sjögren's syndrome (SS) and sicca symptoms was reported in patients with ankylosing spondylitis (AS) and undifferentiated SpA (1). Another link between SpA and CTD is a possible side effect of a DMARD widely used to treat SpA: sulfasalazine (SAS). SAS was reported to induce antinuclear antibodies (ANA) and systemic lupus erythematosus (SLE)-like syndromes such as drug-induced lupus. This report describes a 54-year-old white male, HLA B27-positive AS patient with some syndesmophytes who, after 15 years of disease, developed SS with salivary gland involvement, Raynaud's syndrome and anti-Ro antibodies. Then, 20 years after the onset of AS, he became acutely ill, suffering severe myositis and myocarditis along with swollen hands and highly elevated autoantibody titers recognizing UIRNP; his condition was interpreted as mixed connective tissue disease (MCTD). The patient had been treated with SAS and azathioprine (AZA) alone several times during the last years because he had not tolerated other DMARDs. A combination of both drugs had been prescribed 3 weeks before a severe flair because of progredient high disease activity with painful peripheral arthritis of the MCP and PIP joints which, however, had not shown radiographic erosions. We describe the rare development of MCTD in an AS patient and report, for the first time, the onset of MCTD potentially triggered by sulfasalazine.