<s>[INST] I have a very odd bump beside my knee...it's on the inside. The skin on the outside is a little saggier than on my right knee. When I press down hard, there is a bump and it feels a lot different than my right knee. Also, my knee has been hurting going up stairs, or standing at times. it cracks sometimes when I extend it. [/INST] Hello! Welcome to HCM.This is more likely a William Morrant Baker's cyst.Its a benign swelling in a synovial bursa.Local examination is necessary for diagnosis.In my clinic, I advise excision biopsy for symptomatic cysts.Excision biopsy means the lump is excised & sample is sent for histopathologcal examination.Hope this helps.Wish you a good health.Thanks.Regards. </s>