AKT-1454
A 25-year-old soldier who returned from a tour of Iraq 3 months ago comes to the clinic with a painless ulcer on his forearm. He explains that it began as a small bump and has been growing in size. Upon examination, there is a 4 cm ulcer with a sunken center and a raised firm border. The patient is healthy otherwise and has no other medical issues.
What is the probable diagnosis?