Differential diagnosis of renal adenoma and renal cancer

Since there are many imaging methods for renal cancer, preoperative diagnosis is usually not difficult. However, misdiagnosis and mistreatment still occur from time to time, sometimes resulting in irreparable errors, so patients and doctors must pay attention. Then, the differential diagnosis between renal adenoma and renal cancer is introduced as follows.

(1) For general diagnosis, patients must undergo routine blood, urine and stool examinations, urine cytology, erythrocyte sedimentation rate, blood biochemistry such as liver function, blood sugar, blood calcium, alkaline phosphate level, and chest fluoroscopy or X-ray.

(2) Imaging examination

①B-ultrasound examination: Small renal tumors may not change much, only the renal contours may be slightly lowered, while larger tumors may show enlarged renal contours, abnormal renal structure, uneven echoes, and low echoes. When there is liquefaction, hemorrhage, or necrosis, irregular anechoic dark areas may be seen. When the tumor compresses the pelvis, the renal pelvis may be deformed, displaced, or even interrupted. In the late stage, renal vein or inferior vena cava tumor thrombus may appear. Retroperitoneal lymph node metastasis, etc.

② Intravenous urography: Before contrast, an abdominal plain film is taken to exclude positive stone shadows and calcification plaques. During contrast, contrast agents such as diatrizoate are first injected intravenously. After 5 minutes, the renal parenchyma, renal pelvis, and ureter can be seen one after another. If there is a tumor, the contrast agent will show filling defects and stenosis changes. This method is helpful for observing renal function and diagnosing renal pelvis, ureter, and bladder tumors. The tumors in the renal parenchyma are poorly developed.

③ CT scan: It can clearly show the size and characteristics of the tumor, whether it is convex or invading, the outline, shape, and destruction of the kidney. After enhancement, the density of the tumor passing through the renal parenchyma is lower than that of the renal parenchyma, and it appears as a low-density mass. The density is more uneven than before enhancement, which is conducive to a clearer observation of the tumor. Calcified plaques, silent tumor thrombi in the renal vein or inferior cavity, etc. can all be distinguished.

④ Magnetic resonance imaging: Because the low to medium signal of the kidneys is in sharp contrast to the high signal of the surrounding perinephric fat, T1W1 can well show the relationship between the anatomical structure of the kidney and the surrounding tissues and organs. The MRI signal changes of renal cancer are varied, and even similar to the signal of the renal cortex. Small renal cancers are sometimes difficult to detect. Therefore, MRI should not be used as the first choice for diagnosing renal cancer. However, when CT or other examinations are difficult to determine the nature of the renal tumor, MRI is helpful in determining the source and nature of the tumor.

⑤ Radionuclide bone scanning and imaging examinations. Radionuclide whole-body scanning can detect bone metastasis 3 to 6 months earlier than X-rays. Common sites of bone metastasis are trunk bones, limb bones, skull, etc., but old fractures and degenerative osteoarthritis can also cause similar changes and become false positives.