Under normal circumstances, the hospital will require some items of preoperative blood test, one is for the safety of patients, and the other is for the benefit of the hospital. However, if the symptoms are very minor, it is not surprising that many outpatients directly operate without laboratory tests. Because many patients prefer solving problems to testing.
Personally, if you are afraid of catching any diseases for your own safety, you should agree when the doctor first asks you to have an examination.
Another common tumor is the acne you mentioned, which can't be diagnosed by eye and whole body examination. Specimens must be cut off for pathological examination before the diagnosis can be made. So how did the doctor diagnose you before the operation?
Maybe you won't be happy when I say this, but I'm just saying in fairness that I won't support your idea because of your point of view.