Nails I

This blog originated with my fascination with obscure and brilliant physical exam findings and how they help diagnosis. I know this is not how real medicine works, that most of us no longer look for the right ventricular heave or test for egophony. Indeed, I'm by trade an anesthesiologist and a critical care intensivist; my tools are lab tests, scans, and ventilator readings rather than physical exam pearls. Nevertheless, I love that stuff. So this week we're going to spend some time looking at nails.

Challenge: What is this called?

Image shown under Fair Use.