Why do pathological liars lie so much? How do I handle them?

[CoffeeAddict2016]

Yesterday I posted a thread about one of my colleagues.
It got me thinking, why do pathological liars lie so much? Do you have any experience with pathological liars because I really don't know how to function around, should I just call her out on them?
She'll lie about everything and anything if given the chance. Her lies range from being big whoppers like faking a chronic or illness or claiming her father was an abusive alcoholic to small, white lies that are barely memorable. Every time she lies I just think, WHY?!

(Thread about my colleague I mentioned earlier www.mumsnet.com/Talk/am_i_being_unreasonable/2712578-Leaving-behind-a-mess-for-lazy-lying-coworker-to-tidy-up-AIBU)

I honestly think you need to step back a bit.

You have no evidence she's an actual "pathological liar". So it's best for you to stop obsessing about it all now. Put in a formal complaint.

Agree with above. If you have a problem with her talk to your manager.

Why do they lie so much? Because, I suppose, they have the pathology (disease) of lying.

Lots of reasons: attention seeking; to cover up or deflect from their malevolence; to make them appear more interesting/clever than they are; part of an act to blend in with others who are not character disturbed; because they are laughing on the other side of their face at the gullibility of others; because they are testing the water, looking for gullible targets to manipulate; gaining pleasure and enjoyment from creating dramas and shit stirring; the power trip, the thrill of sabotaging others' lives, including their work to the point of them being sacked or disciplined.
Have absolutely nothing to do with her, ignore her to avoid becoming a target so that when she is looking for a character to assassinate, it is not yours. Do not underestimate the trouble she can cause you. Maybe quietly warn others. No point whatsoever confronting her - she will deny it till the cows come home and, moreover, attribute any craziness to you behind your back instead.

The clue lies in the word pathological. Ignore her lies it but if interferes with your work, then talk to your supervisor.

If you're not qualified to diagnose, don't.

Thanks for the replies, for the record I have plenty of proof she consistently lies.

I have a relative who tells lies. I think he does it to get out of trouble, or to get out of doing things he doesn't want to do. He doesn't think things through though. So often his lies are found out.
I used to work with a girl who told lies too, hers were for attention. She had a big fantasy life going on with a boyfriend who looked like Tom Cruise, (Around Top Gun time, this was years ago). he was in the RAF and the Bomb Squad. He had been first on the scene at the Harrods bomb, he was always away on missions. No one had ever met him. No one bothered confronting her about it. It was harmless enough.

It can be a stand alone disorder or a symptom of other disorders so it could be classed as a mental illness.
I don't think a person does it to piss anyone off. It is not something they can control.

I have known a couple of people like this. Avoid avoid avoid as much as you can. Report if you have proof of something that impacts on their professional competence. If you can alert a sympathetic manager to strong suspicions over a particular work-related issue (eg, say, a meeting missed because of a fabricated appointment) then do so, but only if you can be confident there won't be repercussions for you. Management will probably have their own suspicions too.
I speak with experience of a colleague whose lies ranged from apparently harmless attention-seeking to criminal dishonesty. I was always astonished at how ready most people were to believe it all.