Inflammatory and noninflammatory arthropathy in patients with 18q deletion syndrome.

A 7-year-old girl with 18q deletion syndrome developed chronic progressive polyarticular inflammatory arthropathy. Atypical features of her arthritis included lack of morning stiffness, absence of pain and discomfort, normal acute-phase reactants, and the presence of clinodactyly, low-set thumbs, metatarsus adductus of her feet, and overriding nontender swollen toes. She had a positive antinuclear antibody test, negative rheumatoid factor and anti-cyclic citrullinated peptide, and undetectable immunoglobulin A level. Magnetic resonance imaging of the right knee and the result of the synovial biopsy were consistent with synovitis. She was treated with naproxen, short course of prednisone, and methotrexate with good clinical response that plateaued over time. We analyzed the scarce reports of inflammatory arthropathy in 18q deletion syndrome and proposed an outline for investigating arthropathies in patients with chromosomal aberrations.