If a part obtain really an addition of substance, not dependent on transformation or new formation, it is said to be hypertrophied. This is a new word, but it is a very convenient one. The part suffers an excess of nourishment; it is therefore hypertrophied, over-nourished. […] You may have a part over-nourished without increasing in size—the excess may be such as merely to harden it, so that in one sense induration may be an hypertrophy: but very generally, when a part is over-nourished, it acquires a considerable excess of bulk.
Source: wiktionary