Kidney tumours are
tumour
A neoplasm () is a type of abnormal and excessive growth of tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tissue, and persists ...
s, or growths, on or in the
kidney
The kidneys are two reddish-brown bean-shaped organs found in vertebrates. They are located on the left and right in the retroperitoneal space, and in adult humans are about in length. They receive blood from the paired renal arteries; blood ...
. These growths can be
benign
Malignancy () is the tendency of a medical condition to become progressively worse.
Malignancy is most familiar as a characterization of cancer. A ''malignant'' tumor contrasts with a non-cancerous benign tumor, ''benign'' tumor in that a malign ...
or
malignant
Malignancy () is the tendency of a medical condition to become progressively worse.
Malignancy is most familiar as a characterization of cancer. A ''malignant'' tumor contrasts with a non-cancerous ''benign'' tumor in that a malignancy is not s ...
(
kidney cancer
Kidney cancer, also known as renal cancer, is a group of cancers that starts in the kidney. Symptoms may include blood in the urine, lump in the abdomen, or back pain. Fever, weight loss, and tiredness may also occur. Complications can include spr ...
).
Presentation
Kidney tumours may be discovered on
medical imaging
Medical imaging is the technique and process of imaging the interior of a body for clinical analysis and medical intervention, as well as visual representation of the function of some organs or tissues (physiology). Medical imaging seeks to rev ...
incidentally (i.e. an
incidentaloma
In medical or research imaging, an incidental imaging finding (also called an incidentaloma) is an unanticipated finding which is not related to the original diagnostic inquiry. As with other types of incidental medical findings, they may represen ...
), or may be present in patients as an abdominal mass or
kidney cyst
A renal cyst is a fluid collection in or on the kidney. There are several types based on the Bosniak classification. The majority are benign, simple cysts that can be monitored and not intervened upon. However, some are cancerous or are suspicio ...
,
hematuria
Hematuria or haematuria is defined as the presence of blood or red blood cells in the urine. “Gross hematuria” occurs when urine appears red, brown, or tea-colored due to the presence of blood. Hematuria may also be subtle and only detectable w ...
,
abdominal pain
Abdominal pain, also known as a stomach ache, is a symptom
Signs and symptoms are the observed or detectable signs, and experienced symptoms of an illness, injury, or condition. A sign for example may be a higher or lower temperature than ...
, or manifest first in a
paraneoplastic syndrome
A paraneoplastic syndrome is a syndrome (a set of signs and symptoms) that is the consequence of a tumor in the body (usually a cancerous one), specifically due to the production of chemical signaling molecules (such as hormones or cytokines) by ...
that seems unrelated to the kidney.
Other markers or complications that may arise from kidney tumours can appear to be more subtle, including; low hemoglobin, fatigue, nausea, constipation, and/or hyperglycemia.
Diagnosis
![Contrast-enhanced ultrasonography of benign lesion](https://upload.wikimedia.org/wikipedia/commons/d/d4/Contrast-enhanced_ultrasonography_of_benign_lesion.jpg)
A
CT scan is the first choice modality for workup of solid masses in the kidneys. Nevertheless, hemorrhagic cysts can resemble renal cell carcinomas on CT, but they are easily distinguished with
Doppler ultrasonography
Doppler ultrasonography is medical ultrasonography that employs the Doppler effect to perform imaging of the movement of tissues and body fluids (usually blood), and their relative velocity to the probe. By calculating the frequency shift of ...
(Doppler US). In renal cell carcinomas, Doppler US often shows vessels with high velocities caused by neovascularization and arteriovenous shunting. Some renal cell carcinomas are hypovascular and not distinguishable with Doppler US. Therefore, renal tumors without a Doppler signal, which are not obvious simple cysts on US and CT, should be further investigated with
contrast-enhanced ultrasound
Contrast-enhanced ultrasound (CEUS) is the application of ultrasound contrast medium to traditional medical sonography. Ultrasound contrast agents rely on the different ways in which sound waves are reflected from interfaces between substances. T ...
, as this is more sensitive than both Doppler US and CT for the detection of hypovascular tumors.
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Renal ultrasonography
On renal ultrasonography
Renal ultrasonography (Renal US) is the examination of one or both kidneys using medical ultrasound.
Ultrasonography of the kidneys is essential in the diagnosis and management of kidney-related diseases. The kidneys are easily examined, and most ...
, a solid renal mass
Kidney tumours are tumours, or growths, on or in the kidney. These growths can be benign or malignant (kidney cancer).
Presentation
Kidney tumours may be discovered on medical imaging incidentally (i.e. an incidentaloma), or may be present in pat ...
appears in the US exam with internal echoes, without the well-defined, smooth walls seen in cysts, often with Doppler signal, and is frequently malignant or has a high malignant potential. The most common malignant renal parenchymal tumor is renal cell carcinoma (RCC), which accounts for 86% of the malignancies in the kidney. RCCs are typically isoechoic and peripherally located in the parenchyma, but can be both hypo- and hyper-echoic and are found centrally in medulla or sinus. The lesions can be multifocal and have cystic elements due to necrosis, calcifications and be multifocal (Figure 8 and Figure 9). RCC is associated with von Hippel–Lindau disease, and with tuberous sclerosis, and US has been recommended as a tool for assessment and follow-up of renal masses in these patients.[
]
Classification
There are many forms of kidney tumours:
Malignant (cancerous)
Like other cancers, kidney cancer is measured in stages.
•Stage 1, the tumour has not spread and is localized. This accounts for 65% of cases of kidney cancer and 92.5% of people with stage 1 kidney cancer survive 5 years.
•Stage 2 and 3, the tumour has grown larger and has spread and started to affect regional tissues and lymph nodes. This stage accounts for 17% of kidney cancers and 69% of people are expected to live 5 years with this progression of kidney cancer.
•Stage 4, the kidney tumour has spread to a distant organ or lymph node. 16% of kidney cancers are progressed to this stage and of those people, 12% of them are expected to live 5 years.
* The most frequent, malignant, primary kidney cancer is renal cell carcinoma
Renal cell carcinoma (RCC) is a kidney cancer that originates in the lining of the proximal convoluted tubule, a part of the very small tubes in the kidney that transport primary urine. RCC is the most common type of kidney cancer in adults, resp ...
(RCC) - which has several subtypes:
** Clear cell RCC, an epithelial cell tumour of the kidney that accounts for 65-70% of all RCCs.
** Papillary RCC, a renal tumour that accounts for 10-15% of all RCCs. Males are 1.5 times as likely to develop this type of tumour than females. Papillary RCCs, usually lead to a better prognosis than clear cell RCCs unless the tumour has metastasized.
** Chromophobe RCC, a kidney tumour with usually the best outcome of prognosis. It accounts for 5-7% percent of RCCs.
** Collecting duct RCC
* Mesoblastic nephroma
Congenital mesoblastic nephroma, while rare, is the most common kidney neoplasm diagnosed in the first three months of life and accounts for 3-5% of all childhood renal neoplasms. This neoplasm is generally non-aggressive and amenable to surgical r ...
, a congenital tumor of the kidney's mesenchyme
Mesenchyme () is a type of loosely organized animal embryonic connective tissue of undifferentiated cells that give rise to most tissues, such as skin, blood or bone. The interactions between mesenchyme and epithelium help to form nearly every o ...
(i.e. connective tissue cells) detected prenatally or, more typically, during the first <4 years of life.
* Metastatic tumour, e.g. ovarian carcinoma.
Benign
* Renal oncocytoma
A renal oncocytoma is a kidney tumour, tumour of the kidney made up of oncocytes, epithelial cell, epithelial cells with an excess amount of mitochondria.
Signs and symptoms
Renal oncocytomas are often asymptomatic and are frequently discovered ...
* Cystic nephroma
A cystic nephroma, also known as multilocular cystic nephroma, mixed epithelial stromal tumour (MEST) and renal epithelial stromal tumour (REST), is a type of rare benign kidney tumour.
Symptoms
Cystic nephromas are often asymptomatic. They are ...
* Angiomyolipoma
Angiomyolipomas are the most common benign tumour of the kidney. Although regarded as benign, angiomyolipomas may grow such that kidney function is impaired or the blood vessels may dilate and burst, leading to bleeding.
Angiomyolipomas are st ...
* Metanephric adenoma
Metanephric adenoma (MA) is a rare, benign tumour of the kidney, that can have a microscopic appearance similar to a nephroblastoma (Wilms tumours), or a papillary renal cell carcinoma.
It should not be confused with the pathologically unrelated ...
* Renal medullary fibroma
Surgical complexity
The RENAL Nephrometry Scoring System is used to measure the complexity of kidney tumors for determining whether a renal mass is appropriate for partial or radical nephrectomy, and is estimated by CT scan as follows: The nephrometery score takes into account the size of the tumor (Radius), how much of the tumor is inside or outside of the kidney (Endophytic/Exophytic), how close the tumor is to the urinary collecting system (Nearness), whether the mass is on the anterior or posterior surface of the kidney (Anterior), location relative to polar lines(Lines), and whether or not it is touching the renal artery or vein. This system is used mainly to determine appropriateness of performing a partial nephrectomy where only the tumor itself is removed, or a radical nephrectomy.
Another factor affecting complexity includes renal vein thrombus, which can extend into the inferior vena cava
The inferior vena cava is a large vein that carries the deoxygenated blood from the lower and middle body into the right atrium of the heart. It is formed by the joining of the right and the left common iliac veins, usually at the level of the ...
and into the right atrium
The atrium ( la, ātrium, , entry hall) is one of two upper chambers in the heart that receives blood from the circulatory system. The blood in the atria is pumped into the heart ventricles through the atrioventricular valves.
There are two atr ...
. The degree of extension is commonly graded as follows:
At level 0, the thrombus extends to the renal vein only; at level I, the neoplastic emboli extends into the IVC to no more than 2 cm above the renal vein; at level II, the thrombus reaches into the IVC to more than 2 cm above the renal vein but not to the hepatic vein; moreover at level III, the thrombus reaches into the IVC above the hepatic veins but not above the diaphragm; and finally at level IV, the thrombus extends into the supradiaphragmatic IVC or the right atrium.
Epidemiology
No direct determinant of kidney tumours has been discovered; however, factors that put one at a higher risk of developing them include; smoking, exposure to asbestos and other chemical carcinogens, being obese and/or consuming an unhealthy diet, having a family history of cancer, and alcohol and coffee consumption. The incidence rate of kidney tumours is greater in men than in women. The incidence of kidney tumours is more greatly distributed in North America and Europe than in Asia and South America. The incidence of small renal tumours (masses under 4 cm long) has been increasing since the 1980s. Because kidney tumours are often difficult to detect, the advancement of diagnostic imaging has inherently been correlated with the incidence rate. Although new diagnostic techniques are being utilized and kidney tumors have been diagnosed more often at a lower stage, the mortality rate of the tumours have not fluctuated accordingly.
A higher score indicates a higher difficulty in removing the tumor surgically, potentially making radical (total) nephrectomy
A nephrectomy is the surgical removal of a kidney, performed to treat a number of kidney diseases including kidney cancer. It is also done to remove a normal healthy kidney from a living or deceased donor, which is part of a kidney transplant pro ...
necessary. Specific guidelines vary internationally, but in Hong Kong
Hong Kong ( (US) or (UK); , ), officially the Hong Kong Special Administrative Region of the People's Republic of China ( abbr. Hong Kong SAR or HKSAR), is a city and special administrative region of China on the eastern Pearl River Delt ...
data, patients that underwent partial nephrectomy had scores averaging 7, and those with radical nephrectomy had scores averaging 9.
References
External links
{{Urologic neoplasia
Kidney cancer