After a kidney tumor is found, why can’t we do a biopsy to clarify the benignity or malignancy of the tumor? If we know the tumor is benign at the beginning, can’t we not receive the knife? Many patients will ask this question when they visit our clinic, and here we hope to give you a satisfactory answer. Our biggest concern is that puncture biopsy of kidney tumors is usually not that accurate – it may falsely suggest that the tumor is benign, when in fact it is the opposite! Moreover, some benign kidney tumors, such as pheochromocytoma, are very similar to kidney cancer under the microscope, so it is very difficult for a pathologist to clarify the nature of the tumor by giving them only such a small portion of the tissue for puncture biopsy, and even a very experienced pathology professor would be unable to do anything about it, and any misdiagnosis would be something we would not want to see. Therefore, to make the final determination of benign and malignant, it is still necessary to send the whole tumor for pathological examination after the complete removal of the tumor by the surgeon, and finally the pathologist will make the accurate diagnosis. And after all, puncture is an invasive examination method with certain operational risks, such as bleeding and organ damage. What’s more, the accuracy of puncture biopsy is not much higher than non-invasive examinations like CT or MRI. For most patients, if the CT scan suggests that the tumor may be malignant, then the patient should undergo surgery according to the criteria of malignancy. In addition, surgery for kidney tumor is not as scary as imagined. It is important not to blindly request kidney puncture because of fear of surgery, which sometimes will delay the surgery and miss the chance of tumor eradication. Nowadays, many oncology centers have the technology to perform tumor resection with preservation of normal kidney units, and it is perfectly possible to remove the tumor without damage, or with minimal damage to your kidney function. However, in some specific cases, puncture biopsy is of some significance. For example, if the patient has a history of other cancers, such as lung cancer or lymphoma, then the biopsy can indicate whether the kidney tumor is a metastasis of another cancer lesion in the kidney, and if it is a metastasis, then systemic treatment of the other cancer should be chosen instead of surgical removal of the affected kidney. For elderly patients, if their physical condition does not allow radical nephrectomy or partial nephrectomy for kidney cancer, then puncture biopsy can help us to obtain pathology and then choose less invasive operations such as cryoablation, radiofrequency ablation, interventional embolization and other treatments. In addition, if the kidney tumor itself is very advanced and the opportunity to remove the primary tumor is lost, we can also use puncture biopsy to obtain a pathological diagnosis and then perform targeted systemic systemic treatment based on this pathological diagnosis.