i have a large firm lump behind me knee. What could it be?
541729
Are you sitting on a rock?
1181281
Without more info, it is impossible to even guess here.  Go to your doctor and get it checked out.
697553
You should see a doctor ASAP, it could be an infection or a tumor.
1047836
could be just a cyst, but go to doc and have it checked just to be on safe side
950185
Go to the doctor.  I had a lump before on the right side & it ended up being a cyst (I was able to feel it when I walked, it was bad).  My dr gave me some antibiotics and luckily it burst before I had to have surgery on it.  It can happen when you are pleasuring yourself because your vagina gets engorged and the pressure can be making it more painful for you.  Get it checked out before it gets worse.  Don't be embarrased about telling your doctor-they will want to know so they can accurately diagnose you.  Good luck.
876956
I'd say it has something to do with your  bed!!!!\nif you have not had an injury in the past i'd be getting a new matress or one ot those theraputic foam mats to go over your matress the one with the lumps all over it... Give it a try  anyway and hopefully you'll wake up pain free in the morning.\ngood luck
730134
No one can give you an answer unless they are a doctor, take this lump seriously because it could be something serious. Don't be embarrassed to talk to your parents because it could save your life. A nurse told my son that there was nothing wrong with his testical, and now he has testical cancer and he is going to be a very ill young man of 26 and he had a lump. Best of luck and God guide you to the right decision.
416173
have a doc check it out, could be minor or it could be something serious.
83743
could be your mcl or lcl... ligaments that are on the outside of the knee.. Really should see a doc.
929679
There are a multitude of possibilities. If you are active in sports, it could be Baker's cyst (in which case you'd want to have it checked out). It could be runner's knee and cured by Rest, Ice, Compression, Elevation and even over the counter anti-inflammatory medication. Be careful about anti-inflammatories, however, as no swelling does not mean the injury is cured. You may do further damage to an injury while a pain killer is numbing the symptoms.\n\nIf there was no precipitant or cause for the swelling, it could be more serius. Why take a risk with self diagnosis? \n\nSee a doctor, but don't take anti-inflammatories right before the doctor's visit as he/she will need to see the swelling.
262127
It may be scar tissue that has formed there. I would demand that the doctor due an ultrasound or whatever it took to figure this out.You are your best advocate.
1120164
you should see a doctor, this may be a sign of something serious
969506
not being i a position to know whether you might have been injured in the testicle or to examine it, I cannot say exactly what it might be. Hoiwever, when dealing with lumps or swellings in such a sensitive area one should tend to consult their doctor and have it examined. While it may be nothign serious, it might cuase you even more pain or discomfort in the future. So forget your embarassment and go get a doctor to examine it.
300020
if it is visible than it is above the bone which means chances are it is not a tumor. It is probably a cyst and if he wants to get rid of it, go to a doctor and get it lanced.
596544
Sounds like something more serious. see a md.
448192
A cyst may or may not be a benign tumor. You should see a doctor.
614247
It sounds like a ganglion cyst.  Check out this site and see if this is what it looks like.  http://en.wikipedia.org/wiki/Ganglion_cyst