Inverted Nipple

What could cause an inverted nipple other than breast cancer? I've had a doctor's breast exam more than once, a baseline mamogram (mammogram) and a diagnostifc mamogram (mammogram). These tests came out fine, yet I still have one inverted nipple that I have only had for about 3 years.

[Cleveland Clinic]

Dear mariaboo:  There are several possible causes of inverted nipples.  These can include trauma, inflammation, scarring and others. If there is no evidence of cancer – and it is unlikely not to have manifested itself within 3 years – then you might check with a plastic surgeon.