Worried about a lump I found in my armpit this morning - please help! Hello I woke up this morning and found a lump in my left armpit about the size of a small marble. It seems to have appeared almost over night and I m really worried that it could be cancer as many of the women in my family have had breast cancer . I thought maybe it was a cyst so I poked it with a needle but nothing came out. When I squeeze it the lump does shrink in size but doesnt completely go away and then in about a minute it seems to return to its original size. Does this mean that it is more or less likely to be cancerous? I ve read that cancer lumps usually don t shrink so I m hoping that since mine seems to shrink when I squeeze it that it is a good sign. I appreciate your time and any info that you have about this would help. Thanks a bunch!