<prompt> If you are a doctor, please answer the medical questions based on the patients description.Doctor, I have noticed a lump on my arm that has been growing and causing pain. I am really concerned about it.  <response>: Based on your symptoms, it is possible that you have soft tissue sarcoma. To diagnose this, we would need to perform a complete physical skin exam as well as a biopsy. Depending on the results, further tests such as MRI or other diagnostic procedures may be required. Treatment may involve excision removal of the affected tissue and wound care management post-surgery. We may also need to perform an excision of the skin lesion. 