What condition is represented by inflammatory muscle disease, interstitial lung disease, Raynaud phenomenon, arthritis, and cutaneous manifestations, and in what rheumatologic diseases might you see it?
The patient, a 60-year-old black woman, presented with muscle weakness, Raynaud phenomenon, joint pain, and discoloration of her hands. She had proximal muscle weakness and mild synovitis in her metacarpophalangeal joints. Autoantibody tests were positive for ANA antibodies and 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.
(Photo credit: Michael Guma, DO and Daphne Macbruce, MD)
What is the likely cause of the hyperpigmentation along the palm creases?