By the way, doctor: Can you tell me more about cellulitis?

Q. I developed cellulitis in my arm and didn't realize it was such a serious infection. It took three months to heal without treatment. Can you tell me more about cellulitis?

A. Cellulitis is a bacterial infection of the skin and the soft tissues underneath. It usually affects the skin of the legs and feet, so your experience is a little unusual, but cases affecting the arms, the trunk — even the face — occur often enough. You probably experienced the redness, swelling, tenderness, and warmth that are the main symptoms. Some people also run a fever and have a general rundown feeling.