The answer to the Medical Challenge was #5 Tinea.
Tinea refers to a group of infections caused by fungus. Tinea is also known as "ringworm"..even though it has nothing to do with worms. The ringworm infection is often a well demarcated ring on the face, scalp or body.
The culture of this lesion showed Trichophyton rubrum, a common fungal species that also causes nail infection (