Armpit lump

An armpit lump refers to enlargement of one or more lymph nodes under the arm.


Lumps in the armpit have various causes. Cysts and infections on the surface of the skin of the armpit may be caused by shaving or use of antiperspirants (as opposed to deodorants). This occurs most frequently in adolescents just beginning to shave. Abscesses under the skin may also produce large, painful lumps in the armpit.

Lumps may occur when lymph nodes are swollen due to bacterial or viral infections, vaccinations, and cancer.

Lymph nodes are filters that can catch infectious organisms or cancerous tumor cells. When they do, lymph nodes increase in size and are easily felt. An armpit lump in a woman should be checked by a health care provider immediately, as it may be a sign of breast cancer.


  • Bacterial infection
    • Arm or breast infection
    • Cat scratch disease
    • Ascending lymphangitis
    • Lymphadenitis
  • Cancer
    • Hodgkin's lymphoma
    • Leukemia
    • Non-Hodgkin's lymphoma
  • Fungal
    • Sporotrichosis
  • Other
    • Benign (harmless) cyst
    • Lipomas (harmless fatty growths)
    • Normal breast tissue (breast tissue extends into the armpit area)
  • Vaccinations
    • Allergic reaction possibly caused by sulfa drugs, iodine, or penicillin
    • Measles, mumps, rubella vaccine (rare)
    • Smallpox vaccination
    • Typhoid vaccine
  • Viral infection
    • AIDS
    • Chickenpox
    • Infectious mononucleosis
    • Shingles (herpes zoster)

Home Care

Home care depends on the reason for the lump. Check with your health care provider to determine the cause.

When to Contact a Medical Professional

Call if you have any unexplained armpit lumps. Do not try to diagnose lumps without professional help.

What to Expect at Your Office Visit

Your doctor will perform a physical examination and ask questions about your medical history and symptom, such as:

  • When did you first notice the lump?
  • Is it getting better, worse, or staying the same?
  • Are you breast-feeding?
  • Have you noticed any factors that make it worse?
  • What other symptoms are also present?
  • Is the lump painful?

The physical examination may include palpation -- gently pressing the nodes with the fingertips.

Testing depends on what is found during the physical examination. Tests that may be done include:

  • Blood tests, such as a complete blood count (CBC)
  • Kidney function tests
  • Liver function tests
  • Liver-spleen scan
  • Lymph node biopsy
  • Mammogram
  • Platelet count
  • X-ray of the chest


A lump in the armpit caused by a viral infection will eventually disappear without treatment. A lump in the armpit caused by an allergic reaction will go away after the "trigger" is removed. No treatment is necessary for a lump in the armpit caused by normal breast tissue. Usually, no treatment is necessary for a cyst.

A lump in the armpit caused by a lipoma is harmless, unless it grows so large that it causes discomfort.

The outlook for cancerous lumps depends on the specific type of cancer. See the following for more information:

  • Breast cancer
  • Hodgkin's lymphoma
  • Non-Hodgkin's lymphoma
  • Leukemia

Alternative Names

Lump in the armpit; Localized lymphadenopathy - armpit; Axillary lymphadenopathy; Axillary lymph enlargement; Lymph nodes enlargement - axillary; Axillary abscess