Understanding Male Nipple Discharge: Causes & What to Expect

Question
I am a 23 year old male who has been experiencing spontaneous nipple
discharge on the right side. I have thought to have been experiencing this for
the past 2 years but in recent months it has increased. I do not feel any lumps
or anything else supicious. I have had 2 mammograms before and nothing
supicious turned up. My doctor recommended another mammogram and a
test for my prolactin levels. My questions are what else it could be besides
cancer if nothing turns up abnormal on the mammogram or on the prolactin
test? My discharge is only also on 1 side, would an increase in prolactin affect
both sides? Also, when I squeeze my nipples to check for discharge, nothing
really comes out. Is this odd? Only once did I think I see a very small glimmer
of something. I have been able to squeeze oil out of my nipples if I squeezed
them enough. The only time I see anything is a stain on my shirt above my
nipple.

Thanks.

Answer
This sometimes happen (rarely in males more common in females). Unless there is blood in the discharge it is usually not a sign of any cancer. To check it more thoroughly you could have a galactogram done (a mammogram with x-ray contrast injected into the milk duct from which your discharge comes). You can also complement the mammograms with ultrasound & MRI breast scans and have the discharge checked with exfoliative cytology. The whole phenomenon is somewhat odd, but it does exist as is evident in your case. In some cases we do not know its cause.