An Infected Cystic Swelling in the Armpit

Q: I’m a female and I’m 30 years old. I have had a small pea size lump in my arm pit for about 3 years. I woke up 3 days ago with the lump started hurting and was the size of a walnut. The next day it had a pin size hole through which a green thick awful smelling fluid was coming out. So I went to the ER. They drained it by squeezing really hard. They said it was really thick- like cottage cheese, and they got most of it out. They also said they trimmed the sac a little in my arm pit. They left it open and packed it. They said I still needed to see a surgeon to have the lump removed. What could this lump be? Can it be cancerous? Why did I get this? I’m also on a skin antibiotic pill. Please help me with some information on this. Thank you and God bless.
-By Tiffany


The lump in your armpit is unlikely to be cancerous. Malignant lumps have a tendency to grow and spread. They are unlikely to stay silent for 3 years.

The lump you had could be a sebaceous cyst, which later got infected (due to moisture in the area or maybe some hand maneuvering).

What Is a Sebaceous Cyst?

It is a cystic (fluid filled) swelling formed by occlusion of a duct draining the sebaceous gland.

There are a number of tiny glands called sebaceous glands underneath our skin. These produce sebum, an oily lubricating fluid that prevents dryness and keeps our skin soft.

Quite commonly, the duct draining a gland may get blocked. In such situations, sebum produced by the gland keeps collecting there itself, leading to a cystic swelling called sebaceous gland.

This swelling may stay like this for years. The fluid may get dried up to give a hard lump.

Sometimes, it gets infected and the gland gets filled with cheesy pus.

The treatment is squeezing out the pus.

In cases of long standing lumps, chances of recurrences are pretty high. That is, the remaining lump, after drainage, can again grow to produce a lump.

Treatment for Long Standing Cysts

The treatment involves removing the the whole gland with its covering or capsule. Even a little piece of capsule left can give rise to a lump again.

So, you need to go to a surgeon. He will perform a minor surgery in the area. All he will do is removing the remaining gland contents with the capsule.

Meanwhile, take your skin antibiotics to get rid of any skin infection before the surgery is performed.

Take Care,

Buddy M.D.

Medical Advice (Q&As) on “Infected Sebaceous Cyst in Armpit

  1. Bashir

    I’m a male of 21 yrs living in Africa. 3 weeks back I shaved my armpits, but after 2 days I developed a certain small swelling. I tried applying a balm for 1 week expecting it to diminish but it kept on enlarging and painful. After 1 more week, I went to a physician and he said it was a sebaceous cyst. I was given tablets and told to go back after 3 days if the tablets don’t work & the cyst doesn’t diminish. I went back & have it cut off by the surgeon.
    Qn: What is the best treatment and prevention of such infections?

    1. Buddy M.D. Post author

      Infected sebaceous cyst require antibiotic treatment and simultaneous drainage of pus inside them.

      To prevent them, maintain a good body hygiene. Keep the armpit area clean and dry. It needs to be well ventilated. Wear loose cotton clothes which can absorb excess moisture in the area. Bathe yourself daily.

      Maybe you injured the sebaceous cyst while shaving there, and that’s how it got infected. Be careful while shaving.

  2. Myra Sue Edwards

    I had lumpectomy 10yrs ago, and radiation. At time of surgery had infection at that site,no messer, corrctected with antibiotics. Last 2 yrs, and last 6 months worse with growing and horrible arm and hand pain( 3 doctors have said leave it alone) after build up It seeps fluid tinged with blood-feels larger would this cause the pain I have which is horrible and how can I find a surgeon to do this removal ..

    1. Buddy M.D. Post author

      Where exactly was the lump? Your age? Why were you given radiation therapy? Was that malignant?

  3. Mehwish

    Hi. I have a cyst in the underarm area since 3 or 3 weeks and pus is coming out often. Before it was small then became bigger and painful and most of the fluid came out after that it became same in size and now also pus is coming out sometimes mostly when I clean the area.
    Is it something to worry about? Am scared to go to dr in case is he/she says it is cancerous. I am not that strong to hear this sad thing about myself.. please guide me what should I do? Any effective home remedy?
    Due Thanks

    1. Buddy M.D. Post author

      The lesion is unlikely to be cancerous. You need to see a doctor to get it drained completely.

      This may be an infected sebaceous cyst or hair follicle.


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