Having Painful Lump Behind Knee. No Bruise Appeared. What Should Be Done?
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It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided.
The symptom is suggestive of bakers cyst. It is swelling caused by fluid from the knee joint protruding to the back of the knee.
A Baker cyst may cause no symptoms or be associated with knee pain and/or tightness behind the knee, especially when the knee is extended or fully flexed.
It is confirmed by examination and radiological test. Baker cysts often resolve with aspiration (removal) of excess knee fluid in conjunction with cortisone injection. Medications are sometimes given to relieve pain and inflammation.
For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps.
Hope I have provided the information you needed.
Wish you good health. Take care.