Is Baker's Cyst Anything to Worry About?

QUESTION: I have a soft lump on the back of my knee, that hurts when I
straighten my leg. My doctor told me it was a Baker's Cyst, but I can't find
anything about it in my medical books. Is this anything to worry about? Can
it turn into cancer? It isn't getting any better and I have had it for six
months.
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ANSWER: It's also called a "popliteal cyst," since the back of your knee is
the popliteal area; and it may be the result of a hernia, or pushing outward
of the fibrous capsule of your knee, or of one of the bursa that are located
in this area. A bursa is a sac or sac like formation that contains the thick,
viscid fluid that helps to "oil" the joint and prevent friction. Although a
Baker's cyst (named, not after the bread makers, but Dr. W.M. Baker who
described it first) may occur at any age, but is seen most frequently in men
aged 15 to 30. Its cause is unknown, although trauma to the knee is
suspected, and it never progresses into a cancer of any type. Conservative
treatment using anti-inflammatory medications or aspirating the fluid out of
the cyst and injecting it with corticosteroids may help reduce the symptoms
temporarily. However, your only hope for a permanent solution is to have the
sac removed surgically. The surgeon dissects the cyst away from the
surrounding tissue, and ties of the neck of the sac. When performed properly,
this has a permanent effect and prevents the cyst from increasing in size and
extending down the leg. The pain will also disappear, and you will regain
normal function in your knee and leg.