The discussion about nipple blisters seems to be similar to a situation
I have seem several times, that is a nipple pore, dilated with a white
substance, seeming much like a pimple, and may have a plugged duct
palpable behind it.

One time, after attempting hand expression with no success, I used a
sterile needle (and alcohol swab first) to poke a tiny hole right in
the center of the white bulge.  I was quite shocked to observe a very
small amount of bleeding from the needle site.  I did not realize it
but there must have been a thin layer of skin cells still covering the
plug.  It was not traumatic to the mom, in fact she seemed to feel
nothing during the needle insertion.  The result of this poking about
was a long, curled thread of white cheesy material that was easily
expressed out of the blocked pore.  The mom later reported she used her
finger nail (against my advice) to remove more of the plug, releasing
even more thick, white matter.

Any other similar cases?

Carla D'Anna