Gee, I guess it's time to put my two cents in.  I've tried to restrain
myself and just sit on my  hands and just be the technician downloading
Lactnet for my wife Sarah, the IBCLC of the family.  But looking  over her
shoulder while she read the material, I felt compelled to elaborate on a
comment made by Kathleen A.
     Oh yeah, my credentials are that I'm an internal medicine doc who was
drawn into the study of breastfeeding by my better half.  I am a Medical
Associate with LLL and have researched the literature and spoken on the
topic of breastfeeding and medications at state LLL conferences.  However as
an internist and not being a Ped or Ob-Gyn, my area of "expertise" is
limited when it comes to breastfeeding.
     Nonetheless, let me stick my neck out and provide a word of caution
about the evaluation of palpable breast lumps.  Any lump that is felt and a
*definitive* diagnosis (such as a cyst) can not be made by ultrasound or
other imaging techniques should be biopsied.  An ultrasound or mammogram can
be "normal", i.e. a mass may not show up on these studies, yet a woman may
have a breast cancer.  The physical examination and imaging studies are
complementary.  Either a palpable mass OR an abnormal imaging study requires
further evaluation.  One or the other can pick up problems missed by the
other.  A very sad example:  A dear friend of ours, a 38 yo mother of five,
nursing her 1+ yo was found by her Gyn to have a lump.  A mammogram was done
and apparently based on this info, the Gyn advised the patient to return in
6 months for followup after weaning the child.  To make a long story short,
after that 6 month followup, she had definitive surgery last week and has a
breast cancer with 11 positive lymph nodes.  Her prognosis is grim! :(
     The moral of the story:  A mass in a lactating breast should never
cavalierly be blamed on breastfeeding!
                          Harry Chaikin, M.D.
     P.S.  Sarah wanted me to add that biopsying a lactating breast does not
preclude continuing nursing.