Ulcer with an Undermined Edge

The rapidly expanding lesion began as a small boil in the center of the ulcerated area 4 weeks ago. What underlying process do you suspect?

A 50-year-old woman presented with this ulcerative lesion which she said began approximately one month ago as a small “boil” in the center of the now-enlarged area. She squeezed the initial lesion and treated it with topical antibiotic ointment. The lesion progressively expanded and became extremely painful.

What does this look like to you?