Does eczema usually spread and grow larger or does it stay localized?

Eczema can do both: Eczema can stay localized or spread, depending on the kind of eczema and how well or poorly it is managed. There are sites of predilection for eczema that vary according to age (infants - cheeks, arms, legs), pediatric (behind knees and in front of elbows), adults (trunks, arms, legs, hands). See a dermatologist if your eczema is difficult to manage.