Seizures, executive dysfunction, social disinhibition, incontinence, personality change, etc.
Honestly, I'm pretty sure you could have Google'd that.
Personally, I've never liked the term "prefrontal". Seems kind of nonsensical. It's part of the frontal lobe, not in front of it or underneath it or anything. I know it was defined based on some "prefrontal bone" in embryogenesis or something, but it is still an annoying term.
The problem is differentiating what the lesion CAN cause, and what it DOES cause... As a neuro-oncologist, I see many patients with asymptomatic or minimally symptomatic huge frontal lobe lesions...
That's because we've got two hemispheres. As a former instructor of mine was fond of saying, "you only need one frontal lobe to stay continent and socially appropriate . . ."