<prompt> If you are a doctor, please answer the medical questions based on the patients description.Doctor, I have a lump on my knee, and its been growing in size. Its painful, and Im really worried about it.  <response>: Based on your symptoms, I suspect that you may be suffering from a fungal infection called blastomycosis. Its a rare disease caused by inhaling fungal spores, which can lead to the growth of lumps or masses on the body, including in the knee. Well need to do some tests to confirm the diagnosis and start you on the appropriate treatment plan. 