Causes of armpit lump

Overview

An armpit lump is a swelling or bump under your arm. It can range in size from a small pea to a larger mass and may be tender or painless. Most armpit lumps are harmless, but it is important to have them checked by a doctor to rule out serious causes.

Yes, armpit lumps are very common. Many people will experience one at some point in their life.

Armpit lumps can happen to anyone, but they are more common in people with recent infections, skin conditions, or who shave their underarms. They can also occur after a vaccination or insect bite.

Symptoms

Common symptoms

• A visible or feelable lump under the arm
• Lump may be tender, painful, or painless
• Redness or warmth of the skin over the lump
• Swelling that comes and goes or stays the same

Symptoms in children

• Lump often soft and movable, usually from swollen lymph nodes due to infection
• Might be accompanied by fever, sore throat, or recent illness
• Rarely, a firm, fixed lump that persists may need medical attention

Symptoms in older adults

• Lump may be harder or more fixed in place
• More likely to be related to conditions like lymphoma or metastatic cancer
• Should be evaluated promptly if it is painless, growing, or associated with weight loss or night sweats

Causes

Main causes

• Swollen lymph nodes due to infection (like a cold, flu, or skin infection)
• Lipoma (a harmless, fatty lump)
• Sebaceous cyst (blocked oil gland)
• Folliculitis (infected hair follicle)
• Abscess (collection of pus from infection)
• Less commonly, breast cancer that has spread to lymph nodes, or lymphoma (cancer of the lymphatic system)

Risk factors

• Recent infection or illness
• Shaving or using harsh deodorants that irritate the skin
• Insect bite or sting in the armpit area
• Weak immune system (due to illness or medication)
• Family history of breast cancer or lymphoma (slightly increases risk)

When to see a doctor

See a doctor urgently if:

• Lump that is hard, irregular, or does not move when you push it
• Lump with persistent fever, night sweats, or unexplained weight loss
• Lump that grows quickly over days or weeks
• Lump that causes severe pain or interferes with arm movement

Book a routine appointment if:

• Any lump that has not gone away after 2 to 3 weeks
• Lump that changes in size or feels different over time
• You are concerned about the lump and want peace of mind

Diagnosis

Your doctor will ask about your medical history and symptoms, then feel the lump and examine the surrounding area. They may check for other swollen lymph nodes in your neck, collarbone, or groin.

Tests that may be done

• Ultrasound scan to see the lump’s size, shape, and whether it is solid or fluid-filled
• Blood tests to look for signs of infection or other conditions
• Fine needle aspiration or biopsy – taking a small sample of cells from the lump to examine under a microscope
• If cancer is suspected, you may be referred for further imaging (CT scan) or a specialist appointment

What to expect at your appointment

The diagnosis process is usually straightforward and can be done in a clinic or hospital. Most people get results within a few days to a week. If the lump is found to be harmless, you may not need any further treatment. If it needs treatment, your doctor will explain the options clearly.

Treatment

Treatment depends on what is causing the lump. Many lumps, like those from infections or cysts, may go away on their own or with simple care. Others may need medicine or a minor procedure. Your doctor will recommend the best approach for you.

Self-care at home

• Apply a warm, clean cloth to the lump for 10-15 minutes several times a day to help reduce swelling
• Avoid squeezing or picking at the lump, as this can worsen infection
• Keep the area clean and dry
• Use mild, unscented deodorants and avoid shaving until the lump improves

Medical treatments

If the lump is caused by a bacterial infection, your doctor may prescribe a course of antibiotics. For an abscess, they may need to drain it in the clinic. If the lump is a lipoma or cyst and bothers you, it can be removed with a simple surgical procedure. If the lump is cancerous, treatment will be planned by a specialist team and may include surgery, chemotherapy, or radiation therapy – your care team will explain all options.

When is surgery considered?

Surgery may be recommended if the lump is suspicious for cancer, if it is a large or painful lipoma, or if a cyst keeps coming back. It is usually a minor procedure done under local anaesthetic.

Living with this condition

If you have an armpit lump that is not causing problems, you can live normally. Monitor the lump for any changes and follow your doctor’s advice. If you had treatment, follow any wound care instructions to prevent infection.

Lifestyle tips

• Use gentle, fragrance-free products on your underarms to reduce irritation
• Shave carefully or consider other hair removal methods like trimming
• Wash your underarms daily with mild soap and water
• Avoid tight clothing that rubs against the area

Diet and exercise

There is no specific diet for an armpit lump, but eating a balanced diet and staying active supports your immune system. If you are recovering from treatment, eat well and rest as needed.

Mental health and emotional wellbeing

Finding a lump can cause worry and anxiety. That is a normal response. Talking to your doctor can help ease your mind. If you feel overwhelmed, consider speaking with a counsellor or joining a support group. Remember, most lumps are not serious.

Prevention

Not all armpit lumps can be prevented, because many are caused by common infections or harmless growths. However, you can reduce your risk of infection-related lumps by keeping your skin clean, avoiding cuts, and treating any skin infections promptly.

Complications

If left untreated

• A simple infection could spread to deeper tissues and become a more serious abscess
• An infected cyst could rupture or lead to cellulitis (skin infection)
• If a cancerous lump is not diagnosed early, it may grow or spread to other parts of the body

Long-term outlook

The outlook for an armpit lump is generally good. Most lumps are benign and either go away on their own or are easily treated. For the small number of lumps that are cancerous, early detection and treatment greatly improve outcomes. With modern medicine, many people recover well. Always talk to your doctor about your specific situation.

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