Atlantoaxial subluxation in a patient with mixed connective tissue disease

We describe a 55-year-old woman with an 8-year history of mixed connective tissue disease (MCTD). Her condition was characterized by severe Raynaud's, swollen fingers, digital ulceration and gangrene, esophagitis, polyarthropathy, myositis and restrictive lung function. She consistently had antibodies to U1-RNP. Rheumatoid factor was present in low titer. She developed atlantoaxial subluxation, a feature seen commonly in rheumatoid arthritis, reported in spondyloarthropathy and a small number of patients with systemic lupus erythematosus but not described in MCTD.