An armpit lump is a swelling or bump under the arm. A lump in the armpit can have many causes. These include swollen lymph nodes, infections, or cysts.
Lumps in the armpit may have many causes.
Lymph nodes act as filters that can catch germs or cancerous tumor cells. When they do, lymph nodes increase in size and are easily felt. Reasons lymph nodes in the armpit area may be enlarged are:
Cysts or abscesses under the skin may also produce large, painful lumps in the armpit. These may be caused by shaving or use of antiperspirants (not deodorants). This is most often seen in teens just beginning to shave.
Other causes of armpit lumps may include:
Home care depends on the reason for the lump. Check with your health care provider to determine the cause.
An armpit lump in a woman may be a sign of breast cancer, and it should be checked by a provider right away.
Call your provider if you have an unexplained armpit lump. Do not try to diagnose lumps by yourself.
Your provider will examine you and gently press on the nodes. You will be asked questions about your medical history and symptoms, such as:
You may need more tests, depending on the results of your physical exam.
Reviewed By: Linda J. Vorvick, MD, Clinical Associate Professor, Department of Family Medicine, UW Medicine, School of Medicine, University of Washington, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.