Raynaud phenomenon, joint pain, muscle weakness, and hand discoloration: What is the diagnosis?
A 60-year-old black woman presented with a history of muscle weakness, Raynaud phenomenon, joint pain, and discoloration of her hands. Physical examination showed proximal muscle weakness and mild synovitis in her metacarpophalangeal joints. Laboratory evaluation revealed a mild normochromic normocytic anemia and normal renal function. Urine analysis results were benign. The patient's creatine phosphokinase (CPK) level was elevated at 3435 U/L (normal, lower than 173 U/L). Chest x-ray films revealed mild interstitial changes at the lung bases. Autoantibody test results were positive for antinuclear antibodies and for the presence of anti-Jo1 antibodies, and negative for anti–double-stranded DNA, anti-Smith, anti-U1-RNP, anti-SSA, anti-SSB, HIV, and hepatitis C virus antibodies. A photograph of the patient's hands is shown here.
What is your diagnosis?