An armpit lump is swelling of one or more lymph nodes under the arm.
An armpit lump in a woman should be checked by a health care provider immediately, as it may be a sign of breast cancer.
Lumps in the armpit may have many causes. Lymph nodes are filters that can catch germs or cancerous tumor cells. When they do, lymph nodes increase in size and are easily felt.
Cysts and infections of the skin of the armpit may be caused by shaving or use of antiperspirants (not deodorants). This is most often seen in teens just beginning to shave.
Abscesses under the skin may also produce large, painful lumps in the armpit.
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.
Call your doctor or nurse if you have any unexplained armpit lumps. Do not try to diagnose lumps without professional help.
Your doctor or nurse will examine you and ask questions about your medical history and symptom, such as:
The physical examination may include gently pressing the nodes with the fingertips.
Testing depends on what is found during the physical examination.
Reviewed By: Linda J. Vorvick, MD, Medical Director and Director of Didactic Curriculum, MEDEX Northwest Division of Physician Assistant Studies, Department of Family Medicine, UW Medicine, School of Medicine, University of Washington. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M. Health Solutions, Ebix, Inc.