At the top of this page of posts there is a “sticky” thread from a brilliant poster called RIZZO which is Beginner’s guide to the brain and MRI scans. It explains how a scan works and how it builds up an image. It also gives basic (but brilliant) information about the brain brain and central nervous system - sort of a “Brains for Dummies”. It explains SO much and it is worth its weight in gold. Read it - it explains so much.
Notice that the report you have posted gives the size of the lesion as “up to …” so perhaps this assesment of the lesion is simply a different and more broad-brush description of the same lesion rather than recording that it has “grown”. A lesion is, essentially, scarring, it may fade but it is not like a tumor or cyst that can grow. (Not I am certainly NOT suggesting that the lesion is a brain tumor!!!)