"I'm glad I pushed for that because if I hadn't, I don't know if I'd still be here."
It turned out the tiny little bump was an incredibly rare form of melanoma called spindle cell cancer and it was not just a matter of "cutting it out", as some people believe, Ms Greenslade said.
"The diagnosis was pretty mind-boggling.
"She [the doctor] was as shocked as me.
"I was walking in a daze for a few days, not knowing how to deal with it.
"It's really unusual and it's usually older people that get it."
Ms Greenslade underwent more tests, a sentinel node biopsy and a two-hour surgery called a wide local excision.
It was then a tense five weeks over Christmas waiting to get her results back to see if she was cancer-free. "That's the worst part, you talk to anyone waiting for results, it's horrible.
"You try to be realistic, you try to be positive, but you also have to prepare yourself it might not be good news."
To her relief, she got the all-clear and did not need further treatment.
"I was really scared about turning 40, but I was kind of happy to get there because I might not have been there, so it certainly made me think about a lot of things."
Ms Greenslade said the hardest part of her journey has been healing physically and emotionally.
She could not hide her scars and found it difficult when people stared. Just a few months ago, she cut her hair short, which was a big step.
She said the realisation of what she had gone through hit hard last year.
"I think maybe I put a lot of it aside and kind of got on with things."
Ms Greenslade has regular skin check-ups and still fears it will come back.
"You never feel completely over it."
She said she now tells people, especially her children, to be proactive about their health, check their skin routinely, get tested, and get second opinions.
"If you're feeling iffy about something, pay attention to your intuition and push.
"It's better to be wrong and 'oh that was a waste of time' than not do anything."
She is now studying psychology full-time through the Open Polytechnic, with the aim of counselling young people with cancer.
Throughout her journey, she was inspired by the attitude of young people dealing with cancer.
"Kids are amazing, they are so resilient; no matter how frightened I was of having surgery, I kept that in the back of my mind."