Underarm Lumps: Causes and Concerns About Pus

There is a small hard lump inside the armpit that produces pus when pressed?

Hello Doctor,
1.
About a month ago, I noticed a pimple-like bump on the surface of my armpit, which disappeared after a while.
However, I later noticed a round, firm lump about 0.5-1 cm in size inside my armpit.
I can pinch it between my thumb and index finger, and it is not visible from the outside nor does it hurt.
If I squeeze it hard, some pus comes out.
It has been present for a month (or possibly longer, as I may not have noticed it before).
Could this be something concerning?
2.
Additionally, there is a bump on my back that is about 1 cm in size and has been there for several years.
It usually does not hurt, but if I accidentally scrape it or squeeze it hard, it can be very painful.
What could this possibly be? Thank you, Doctor!

woo, 20~29 year old female. Ask Date: 2024/04/15

Dr. Hu Ziren reply Oncology

It may just be some pustules, folliculitis, or acne; observation is recommended.

Reply Date: 2024/04/15

More Info

When it comes to understanding lumps in the underarm area, it’s essential to consider various potential causes and the implications of pus formation. Based on your description, let’s break down your concerns regarding the lump in your armpit and the one on your back.

1. Underarm Lump: The lump you described in your armpit, which is about 0.5 to 1 cm in size, hard, and can be squeezed to expel pus, is likely a sebaceous cyst or an infected hair follicle (folliculitis). Sebaceous cysts are common and occur when a hair follicle becomes blocked, leading to the accumulation of sebum (the oily substance produced by sebaceous glands). If the cyst becomes infected, it can fill with pus, leading to the symptoms you described.
While these lumps are usually benign, the presence of pus indicates an infection, which may require treatment. If the lump is painful, growing, or accompanied by fever, it’s crucial to seek medical attention. A healthcare provider may recommend draining the cyst or prescribing antibiotics if an infection is present. It’s important not to squeeze or pop the lump yourself, as this can worsen the infection or lead to scarring.

2. Back Lump: The lump on your back that has been present for several years and is painful when scraped or squeezed could be another type of cyst, such as a lipoma, which is a benign tumor made of fatty tissue. Lipomas are generally soft, movable, and painless, but they can become tender if they are irritated or if they press on nearby nerves.
Another possibility is that it could be a dermatofibroma, a benign growth that can feel firm and may be painful if traumatized. These growths are usually harmless but can be removed if they cause discomfort or for cosmetic reasons.

In both cases, while the lumps may not be immediately concerning, monitoring their size, shape, and any changes in symptoms is essential. If you notice any rapid growth, changes in color, or if they become increasingly painful, it’s advisable to consult a healthcare professional for a thorough evaluation.

Additional Considerations:
- Diagnosis: A healthcare provider may perform a physical examination and, if necessary, imaging studies (like an ultrasound) or a biopsy to determine the exact nature of the lumps.

- Treatment Options: Treatment may range from observation for benign lumps to surgical removal if they are bothersome or suspected to be malignant.

- Hygiene and Care: Maintaining good hygiene in the affected areas can help prevent infections. Avoid tight clothing that may irritate the skin and lumps.

Conclusion:
While lumps in the underarm and back can often be benign, the presence of pus and pain warrants a closer look. It’s always best to err on the side of caution and consult a healthcare provider for an accurate diagnosis and appropriate management. Regular self-examinations and awareness of changes in your body can help in early detection and treatment of potential issues.

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