Which of the following regresses in size with age: hemangioma or vascular malformation?

Hemangiomas are benign tumors made up of blood vessels and are commonly seen in infants and young children. One of the most distinctive features of hemangiomas is their natural tendency to regress in size as the child ages. Typically, hemangiomas will grow rapidly during the first few months of life and then enter a period of involution, often shrinking significantly or disappearing altogether by the time the child reaches several years of age. This characteristic is what sets hemangiomas apart from vascular malformations.

On the other hand, vascular malformations are generally present at birth and do not regress over time. They are abnormal collections of blood vessels that can grow proportionally with the individual but do not exhibit the same involutional behavior as hemangiomas. Because of these differences in growth patterns, hemangiomas are the correct answer in the context of this question.