bald spot
bald patch

More so than the bald patch at the back of his head.

I ignore him carefully, looking at the bald patch of the friendly one.

For some, the problem will be short-lived and limited to one or a few bald patches.

With Bates these days it is a game of spot the bald patch.

I reach up to my own head; a bald patch.

There was a bald patch on the peak of his skull.

Too short, and it has a bald patch on one side.

What I noticed right away, however, was that she had a few bald patches on top of her head.

I noticed a small bald patch on the crown of his head.

He used a hair-piece to cover a bald patch on top of his head.