<s>[INST] Hello. I got a kind of a lump on my knee cap and inside i can move something on my knee it feels like a little ball. It don t hurt as much but when i press down i just get a little pain nothing much. So can u help me what is this? Pain is nothing really just a little tiny pain. [/INST] Hi! Thanks for writing to us sharing your problem of a lump on the knee! As per your description, the lump is on the knee cap, mobile, painless but slightly tender...therefore, as per my experience of needle biopsies, I can suggest few possibilities as below:1. Bursa or ganglion like degenerative cystic lesion 40% possibility2. Benign stromal or soft tissue tumor like lipoma, neurofibroma or hematoma 20% possibility3. Synovial effusion, herniation or patellar dislocation 20% possibility4. Neoplastic tumors like fibrous, histiocytoma, synovial sarcoma etc. 20% possibility, it should be examined and investigated properly before a radical excision by an orthopedic or general surgeon; please see one surgeon at your area for the detailed examination and needle biopsy if necessary! Wishing you good health, regards, </s>