What are the methods for checking kidney cancer?

Kidney cancer is a malignant tumor that occurs in the kidney. Due to its hidden onset, it is difficult to diagnose and treat kidney cancer patients in the early stage, which often causes patients to miss the best treatment opportunity. Therefore, in order to diagnose and treat kidney cancer early, experts have introduced the following methods for early diagnosis of kidney cancer.

1. General examination:

Hematuria is an important symptom, and polycythemia occurs in 3% to 4% of cases. Progressive anemia may also occur. In bilateral renal tumors, total renal function usually remains unchanged, but the erythrocyte sedimentation rate increases. Some patients with renal cancer do not have bone metastasis, but may have symptoms of hypercalcemia and increased serum calcium levels. After renal cancer resection, the symptoms are quickly relieved and the blood calcium returns to normal. Sometimes liver dysfunction may develop, but if the tumor kidney is removed, it can return to normal.

2. X-ray angiography is the main method for diagnosing renal cancer (1) X-ray film:

Plain X-rays can show that the kidney is enlarged and its contour has changed. Occasionally, there is tumor calcification, localized or widespread flocculent shadows within the tumor, and calcification lines or shells around the tumor. Kidney cancer is especially common in young people.

(2) Intravenous urography Intravenous urography is a routine examination method. It cannot show tumors that have not yet caused the renal pelvis and calyces to deform, and it is difficult to distinguish whether the tumor is renal cancer, renal angiomyolipoma, or renal cyst, so its importance is reduced. Ultrasound or CT examination must be performed at the same time for further identification. However, intravenous urography can understand the function of both kidneys and the condition of the renal pelvis, calyces, ureters, and bladder, which has important reference value for diagnosis.

(3) Renal arteriography:

Renal artery angiography can reveal tumors that are not deformed by urinary system angiography. Renal cancer is manifested by new blood vessels, arteriovenous fistulas, pooling of contrast agents, and increased capsular blood vessels. Angiography has great variability, and sometimes renal cancer may not be visualized, such as tumor necrosis, cystic changes, arterial embolism, etc. When necessary, adrenaline can be injected into the renal artery to cause normal blood vessels to contract, but tumor blood vessels will not respond.

Experts remind: In relatively large renal cancers, renal artery embolization can also be performed during selective renal artery angiography to reduce bleeding during surgery. Renal artery embolization can be performed as a palliative treatment for patients with renal cancer that cannot be surgically removed and severe bleeding.

3. Ultrasound Scan:

Ultrasound examination is the simplest and non-invasive examination method and can be used as part of routine physical examination. Any mass in the kidney that is larger than 1 cm can be detected by ultrasound scanning. It is important to distinguish whether the mass is renal cancer. Renal cancer is a solid mass. Because it may have bleeding, necrosis, and cystic changes inside, the echo is uneven and generally low-echo. The boundary of renal cancer is not very clear, which is different from renal cysts. Space-occupying lesions in the kidney may cause deformation or rupture of the fat in the renal pelvis, calyx, and renal sinus. Papillary cystadenocarcinoma of the kidney looks like a cyst on ultrasound examination and may have calcification. When it is difficult to distinguish between renal cancer and cysts, puncture can be performed. Puncture under ultrasound guidance is relatively safe. The puncture fluid can be examined for cytology and cyst contrast. Cyst fluid is often clear, free of tumor cells, and low in fat. When the cyst wall is smooth during contrast imaging, it can be confirmed that it is a benign lesion. If the puncture fluid is bloody, a tumor should be considered. Tumor cells may be found in the aspirate. When the cyst wall is not smooth during contrast imaging, it can be diagnosed as a malignant tumor. Renal angiomyolipoma is a solid tumor in the kidney. Its ultrasound manifestation is a strong echo of fat tissue, which is easy to distinguish from renal cancer. When renal cancer is found by ultrasound examination, attention should also be paid to whether the tumor has penetrated the capsule and perirenal fat tissue, whether there are enlarged lymph nodes, whether there are cancer thrombi in the renal vein and inferior vena cava, and whether there is liver metastasis.

4. CT scan:

CT plays an important role in the diagnosis of renal cancer. It can detect renal cancer that has not caused changes in the renal pelvis and calyx and has no symptoms. It can accurately measure the tumor density and can be performed in outpatient clinics. CT can accurately stage. Some people have calculated its diagnostic accuracy: 91% of invasion of the renal vein, 78% of perirenal spread, 87% of lymph node metastasis, and 96% of involvement of nearby organs. Renal cancer CT examination shows a mass in the renal parenchyma, which can also protrude from the renal parenchyma. The mass is round, quasi-round or lobed, with clear or blurred boundaries. It is a soft tissue mass with uneven density during plain scan. The CT value is >20Hu, usually between 30 and 50Hu, slightly higher than the normal renal parenchyma, or similar or slightly lower. The internal unevenness is caused by hemorrhage, necrosis or calcification. Sometimes it can be manifested as a cystic CT value, but there are soft tissue nodules on the cyst wall. After intravenous injection of contrast agent, the CT value of normal renal parenchyma reaches about 120Hu, and the CT value of the tumor also increases, but it is significantly lower than the normal renal parenchyma, making the tumor boundary clearer. If the CT value of the mass does not change after enhancement, it may be a cyst. The diagnosis can be confirmed by combining the CT value before and after contrast medium injection as liquid density. In necrotic foci in renal cancer, renal cystadenocarcinoma, and after renal artery embolization, the CT value does not increase after contrast medium injection. Because renal angiomyolipoma contains a large amount of fat, the CT value is often negative and the interior is uneven. After enhancement, the CT value increases, but it still shows fat density. During CT examination, oncocytoma has clear edges and uniform internal density, and the CT value increases significantly after enhancement.

The above is some knowledge about kidney cancer examination that we have prepared for you today. We hope it can be helpful to you. If you have any other needs, you can also consult our online consulting experts. We are always ready to answer your questions and give you more detailed guidance.

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