A Japanese Patient with Anti-PM/Scl and Centromere Antibody-Positive Scleroderma-Amyopathic Dermatomyositis Overlap Syndrome Who Developed Renal Crisis.

Anti-PM/Scl antibodies are associated with the overlap syndrome of systemic sclerosis and dermatomyositis/polymyositis (SSc-DM/PM), and are found in 50% of SSc-DM/PM cases in Europe and the United States, whereas they are rare in Japan. We report a case of an 80-year-old Japanese female with SSc-amyopathic dermatomyositis (ADM) overlap syndrome, who developed scleroderma renal crisis (SRC), a complication of SSc. She had positive antinuclear antibodies in a discrete-speckled and nucleolar pattern and anticentromere antibodies and anti-PM/Scl antibodies were confirmed by ELISA and immunoprecipitation, respectively. The incidence rate of SRC in SSc patients varies significantly depending on the specificity of autoantibodies, with the highest incidence of ~50% in anti-RNA polymerase III antibody positive patients, followed by ~10% in anti-PM/Scl and lower incidence of 0.45% in anticentromere antibody-positive cases. Anti-PM/Scl antibodies are uncommon in Japanese patients presumably due to its strong association with certain HLA haplotype that is rare in Japanese. Clinical significance of anti-PM/Scl antibodies in Japanese patients will need to be clarified with accumulation of cases in future studies.