Medical Challenge - What's the Diagnosis?

The New England Journal of Medicine diagnostic challenge is aimed at physicians but anyone can play. This patient has skin lesions (click on image for a better view) that are non-tender, non-itchy and slowly growing. What lab test would cinch the diagnosis? 1. 17-hydroxyprogesterone2. Angiotensin-converting enzyme3. Anti-tissue transglutaminase antibody4. Prolactin5. Vitamin B6 The