Lump in Armpit
A lump in the armpit can be worrying, but common issues like swollen lymph nodes, cysts, or infections usually cause it. Most armpit lumps are harmless and often result from the body’s response to infection or skin irritation.
Other possible causes include ingrown hairs, irritation from shaving or deodorant, or blocked hair follicles. Some armpit lumps signal more concerning conditions, such as tumors or cancer. Knowing the possible causes helps people decide when to seek medical advice.
Definition of Symptom
An armpit lump is a swelling, bump, or area of fullness under the arm. These lumps can vary in size, texture, and how deep they sit under the skin. Sometimes, they are soft and move easily, while other times they feel hard and fixed. Enlarged or swollen lymph nodes often cause armpit lumps. Lymph nodes help the immune system and may grow when the body fights infection.
In some cases, these lumps are painless, while in others they can cause discomfort or pain. People may find just one lump or notice several lumps in the armpit. Painful lumps are more likely linked to infections or abscesses. Common features of an armpit lump include:
| Feature | Description |
|---|---|
| Size | Small as a pea to larger |
| Texture | Soft, firm, or hard |
| Mobility | Moves or feels fixed |
| Pain | May hurt or not hurt |
Some lumps come from cysts or fatty growths, while others result from irritation, such as shaving or ingrown hairs.
Possible Causes/Diseases Condition
Many things can cause a lump in the armpit. Swollen lymph nodes often swell in response to infection in the arm, breast, or chest. Infections can be bacterial or viral. Sometimes, fungal infections cause a lump. Skin irritation from shaving, deodorant, or chafing can cause local swelling.
More serious causes include breast cancer and lymphoma. Breast cancer can cause hard, painless lumps near the armpit area. Lymphoma, a cancer of the lymphatic system, may also appear as a painless lump. Other cancers, such as leukemia or melanoma (skin cancer), sometimes cause swelling in this area.
In rare cases, a fibroadenoma, a non-cancerous breast tumor, may be the cause. Hidradenitis suppurativa is a long-term skin condition where sore bumps develop under the skin, often in the armpits. These lumps may be painful and can fill with pus. Autoimmune disorders like systemic lupus erythematosus can sometimes cause lymph nodes to swell, leading to lumps under the arm.
| Cause | Type |
|---|---|
| Swollen lymph nodes | Infection, immune response |
| Breast cancer | Malignant tumor |
| Lymphoma | Cancer of the lymphatic system |
| Hidradenitis suppurativa | Skin condition |
| Fibroadenoma | Benign breast tumor |
| Fungal infections | Infection |
| Leukemia | Blood cancer |
| Systemic lupus erythematosus | Autoimmune disorder |
| Melanoma (skin cancer) | Malignant tumor |
Other Non-Disease Causes
A lump in the armpit can also come from things that are not related to disease or infection. These causes are usually not dangerous and often go away on their own. Cysts often show up as small, round bumps under the skin when oil or sweat glands get blocked. Most cysts are painless and soft to the touch.
Lipomas are soft, fatty lumps that grow slowly beneath the skin. They are not cancer and do not usually cause pain or other symptoms. Using deodorants or antiperspirants can sometimes cause irritation or allergic reactions. This can lead to swelling, redness, or small lumps in the armpit area.
Shaving the underarms can also cause lumps, often due to ingrown hairs, which can feel like small, tender bumps. Vaccines given in the upper arm may cause lymph nodes in the armpit to swell. This is a normal immune response and should go away after a few days. Acne can develop in the armpit, especially in people who sweat a lot or use oily products.
These bumps may be red, tender, or filled with pus. Some people notice itching or mild irritation before a lump forms. This usually comes from skin irritation, allergies, or blocked pores. Below is a quick reference table of common non-disease causes:
| Cause | Main Feature | Usual Symptom |
|---|---|---|
| Cyst | Blocked gland | Round, smooth bump |
| Lipoma | Fat tissue growth | Soft, painless lump |
| Deodorant/Allergy | Skin reaction | Swelling, redness |
| Shaving | Ingrown hair | Tender, small lump |
| Vaccine | Immune response | Swollen lymph node |
| Acne | Blocked pore | Red, painful bump |
How It Causes the Symptom
The body often reacts to infection or injury by making the lymphatic system respond, which can cause lymph nodes to swell and create a lump under the skin. Irritation or infection of the hair follicles can also lead to inflammation and small lumps. Shaving, using certain deodorants, or blocked sweat glands can cause these bumps.
Sometimes, a cyst or fatty growth develops, usually feeling soft and movable. A lump can also form if there is a deeper issue, like a chronic disease or, rarely, cancer. Family history can increase risk, especially for conditions that affect lymph nodes or the breast.
Doctors may use imaging tests—such as MRI or ultrasound—to look inside the armpit and better understand the lump. If the cause is unclear, especially if the lump does not go away or feels hard and fixed, a biopsy may be needed. Common ways lumps form in the armpit:
- Infection causing lymph node swelling
- Irritated or infected hair follicle
- Cyst or abscess under the skin
- Growths related to chronic conditions
Possible Complications
Some armpit lumps are harmless, but others can lead to serious health issues if not treated promptly. Infections may spread, causing fever or ongoing pain. If a lump comes from a bacterial infection, antibiotics often help prevent more problems. A swollen lymph node in the armpit may sometimes point to a more serious issue, such as cancer. Signs that may be linked to cancer include:
- Night sweats
- Unexplained weight loss
- A lump that gets larger or does not go away
If cancer causes the lump, treatment options may include chemotherapy, surgery, or radiation, depending on the type and stage. In rare cases, untreated abscesses in the armpit can cause infection to spread deeper or even into the bloodstream, leading to a more severe illness needing urgent medical care.
Table: Signs That May Mean Complications
| Symptom | What It May Mean |
|---|---|
| Red, hot, painful lump | Infection or abscess |
| Fever | Widespread infection |
| Firm, unmoving lump | Possible tumor or cancer |
| Weight loss, night sweats | Possible lymphoma |
When to Seek Medical Attention
Knowing when to see a doctor about a lump under the armpit is important. Not all lumps are serious, but some can signal health problems. See a doctor if the lump:
- Lasts more than two weeks
- Gets bigger
- Feels hard or does not move when touched
- Hurts or causes discomfort
- Looks red, feels warm, or leaks fluid
- Is not linked to a recent infection or vaccine
If you notice other symptoms with the lump, like unexplained weight loss, fever, night sweats, or tiredness, these could point to a more serious problem. Anyone with a history of cancer or breast problems should be especially careful. If you find a lump during a breast self-exam, tell your healthcare provider.
Watch for Emergency Signs
| Symptom | Action |
|---|---|
| Difficulty breathing | Call 911 |
| Chest pain | Call 911 |
| Rapid swelling | Get care now |
If you are unsure about any new or changing armpit lump, talk with a doctor.
