Cellulitis and Erysipelas

The anatomical illustration above demonstrates a pathological process primarily involving the hypodermis and deep fat layers. Which of the following skin infections is characterized by inflammation and infection predominantly at this anatomical depth?

The clinical image of a child's lower trunk and limbs shown above demonstrates a rapidly spreading, bright red, painful, and indurated skin lesion with a sharply demarcated, raised border. Which of the following is the most likely diagnosis?