Very weird lump in armpit

[Paranoid_girl]

A little over a month ago, a lump started growing in my left armpit. It was hot, tender, painful, and eventually about the width of a quarter. About a week later, it started decreasing in size, until it shrunk to about the size of a dime. By then it was no longer hot or painful, barely noticeable. Then at about 3 weeks it began growing again, not painful, but noticeably larger. After a few days, it started shrinking again. As of right now, it is currently increasing in size, but not extremely. It is not painful or bothersome, but I'm worried about WHAT it is, WHY it's not going away, and WHY it keeps changing in size. It's not an ingrown hair--there's no head. Could it be a tumor? I didn't think tumors grew and shrank, though. For reference, I am a 17 year old girl, with no medical history of abnormal diseases or conditions.

[Paranoid_girl]

Hi Dr. Santos,

No other symptoms are present. I feel perfectly fine and don't even feel or see the armpit unless I lift my arm up and closely inspect it. My main concern is the growth and shrinking of it over the course of the month without any other symptoms. I was briefly ill (autumn cold, everyone I was around had it too) but during that period of time, the lump didn't change. Thanks for your feedback.

Nancy

[Dr Santos]

Hi,
What other symptoms are present? An armpit lump may be caused by a variety of issues such as inflamed lymph nodes, cysts and infections of the skin of the armpit and  may be caused by shaving or use of antiperspirants, lipoma,  and even arm or breast infection as well as malignancy.  For proper diagnosis, it is best that you have this checked by your doctor. Direct clinical examination and imaging studies may also help. Take care and do keep us posted.