The picture is most consistent with a plantar wart.

A common presentation in clinical practice as well as Pediatric Board Exams  is heel pain where  the parent suspects the child stepped on glass or another foreign body.

Depending on the size, it can be presented as  acute severe heel pain. This could be a curve ball since, even though it is parented as an acute problem, it is really a chronic problem that was just noticed. 

In the question they might divert you into suspecting it is an injury by noting it was detected after playing basketball or another sport.

The Differential would of course include

• Calcaneal Osteomyelitis
• Cellulitis / Abscess
• Foreign Body
• Tendinitis

Pay attention to what is being described and don’t be diverted by the red herrings