<s>[INST] i have a large lump on my back , its been there for a few years now ,i was told by gp it was a cyst and nothing to worry about so i left it , and forgot about it , today my sister came round and said she could see a black dot on it, so i told her to squeeze it. a yellow, darker than normal pus came out , it was quite solid in form and had a cheesy smell that was really strong. it took over half an hour before it finally stopped . would just like some advice on it please [/INST] Hi ! Good morning. I am Chat Doctor answering your query. With your history, it is typical of a sebaceous cyst with a black dot on it, which discharges a smelly cheesy material on squeezing. This is a benign cyst without any fear of turning into a malignancy. However, to prevent other complications like recurrent infections, abscess formation, it is advisable to get it operated and send it for a histopathological study to confirm the diagnosis. If I were your doctor, I would refer you to a general surgeon who after examining you physically and a preoperative check-up, might advise you to get it operated soon. I hope this information would help you in discussing with your family physician/treating doctor in further management of your problem. Please do not hesitate to ask in case of any further doubts. Thanks for choosing Chat Doctor to clear doubts on your health problems. Wishing you an early recovery. Chat Doctor. </s>