Lump behind knee popped

[Grizzz]

Hi, I've had this tiny little lump behind my knee, maybe half the size of a dime, for quite a few years. over the last few days however, it has ballooned up to about half the size of a ping pong ball. Just a little while ago, it seemed to pop, without any pain or anything, just found blood leaking down the back of my leg, along with a foul smelling pus. Any idea what this is?

[Bhupinder Kaur, MD]

Hello,
They seem like boils or furuncle. Boils are caused by infection of the hair follicle by staph aureus. . Hair follicles that are blocked by greasy creams, petroleum jelly, or similar products are more vulnerable to infection. Bacterial skin infections can be spread by shared cosmetics or washcloths, close human contact, or by contact with pus from a boil or carbuncle.Treatment includes antibiotics and pls do not touch or pick them up.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.

[Arti Sharma, M.D.]

Hello,
Without a complete evaluation I may not be able to confirm the exact cause .It is possible that you have been suffering from Bakers cyst which has ruptured. A Baker cyst is swelling caused by fluid from the knee joint which may have protruded to the back of the knee.Osteoarthritis, cartilage tears, rheumatoid arthritis any of these conditions can lead to the formation of this cyst. There can be protrusion of fluid down the leg between the muscles of the calf or rupture of the cyst. Diagnosis can be confirmed by examination and radiologically.Other possibility is phlebitis of the leg. See a doctor. Treatment will be specific based on the cause. Do write to me again.
Best wishes and regards!