How different does a pattern have to be to publish it?

Ive been looking for a crochet beanie pattern that has a pretty open stitch that works well for men but i couldnt really find exactly what i was looking for. I did find a design that was ok but the pattern was too tight to comfortably breath while wearing it (Trying to crochet a beanie to wear in texas during the summer, I know its crazy but its for a friend who is trying to hide a surgery scar).

I ended up making some modifications to the pattern i found to open it up and was thinking other people might be interested in this kind of design but i wasnt sure if this kind of thing is ok or frowned upon to modify someone elses pattern then publish it.

What do you think?