| Kidney tumour | |
|---|---|
| Other names | Kidney tumors, renal tumours |
 | |
| Micrograph of a renal oncocytoma, a type of benign kidney tumour. H&E stain. | |
| Specialty | Oncology, nephrology |
Kidney tumours are tumours, or growths, on or in the kidney. These growths can be benign or malignant (kidney cancer).
Kidney tumours may be discovered on medical imaging incidentally (i.e. an incidentaloma), or may be present in patients as an abdominal mass or kidney cyst, hematuria, abdominal pain, or manifest first in a paraneoplastic syndrome that seems unrelated to the kidney. [1] 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. [2]
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 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, as this is more sensitive than both Doppler US and CT for the detection of hypovascular tumors. [3]
On renal ultrasonography, a solid renal mass 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. [3]
There are many forms of kidney tumours:
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. [4]
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: [7] 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. [8]
Another factor affecting complexity includes renal vein thrombus, which can extend into the inferior vena cava and into the right atrium. 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. [9]
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. [10] The incidence rate of kidney tumours is greater in men than in women. [11] 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. [12]
| Score | |||
|---|---|---|---|
| Component | 1 point | 2 points | 3 points |
| R (radius, maximal diameter) | ≤ 4 cm | > 4 and < 7 cm | ≥ 7 cm |
| E (exophytic/endophytic) | ≥ 50% exophytic | < 50% exophytic | Completely endophytic |
| N (nearness to collecting system/renal sinus) | ≥ 7 mm | > 4 and < 7 mm | ≤ 4 mm |
| A (anterior/posterior locator) | A descriptor of “a,” “p,” or “x” is assigned for tumour location. | ||
| L (location relative to polar lines) | Entirely below lower polar or entirely above upper polar line | Mass crosses polar line | 50% of the mass is across polar line, or mass is entirely between polar lines, or mass crosses axial midline |
A higher score indicates a higher difficulty in removing the tumor surgically, potentially making radical (total) nephrectomy necessary. Specific guidelines vary internationally, but in Hong Kong data, patients that underwent partial nephrectomy had scores averaging 7, and those with radical nephrectomy had scores averaging 9. [13]
Von Hippel–Lindau disease (VHL), also known as VonHippel–Lindau syndrome, is a rare genetic disorder with multisystem involvement. It is characterized by visceral cysts and benign tumors with potential for subsequent malignant transformation. It is a type of phakomatosis that results from a mutation in the Von Hippel–Lindau tumor suppressor gene on chromosome 3p25.3.
Liver tumors are abnormal growth of liver cells on or in the liver. Several distinct types of tumors can develop in the liver because the liver is made up of various cell types. Liver tumors can be classified as benign (non-cancerous) or malignant (cancerous) growths. They may be discovered on medical imaging, and the diagnosis is often confirmed with liver biopsy. Signs and symptoms of liver masses vary from being asymptomatic to patients presenting with an abdominal mass, hepatomegaly, abdominal pain, jaundice, or some other liver dysfunction. Treatment varies and is highly specific to the type of liver tumor.
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, responsible for approximately 90–95% of cases. It is more common in men. It is most commonly diagnosed in the elderly.
Kidney cancer, also known as renal cancer, is a group of cancers that starts in the kidney. Symptoms may include blood in the urine, a lump in the abdomen, or back pain. Fever, weight loss, and tiredness may also occur. Complications can include spread to the lungs or brain.
In medical or research imaging, an incidental imaging finding is an unanticipated finding which is not related to the original diagnostic inquiry. As with other types of incidental medical findings, they may represent a diagnostic, ethical, and philosophical dilemma because their significance is unclear. While some coincidental findings may lead to beneficial diagnoses, others may lead to overdiagnosis that results in unnecessary testing and treatment, sometimes called the "cascade effect".
A Klatskin tumor is a cholangiocarcinoma occurring at the confluence of the right and left hepatic bile ducts. The disease was named after Gerald Klatskin, who in 1965 described 15 cases and found some characteristics for this type of cholangiocarcinoma
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 procedure.
Birt–Hogg–Dubé syndrome (BHD), also Hornstein–Birt–Hogg–Dubé syndrome, Hornstein–Knickenberg syndrome, and fibrofolliculomas with trichodiscomas and acrochordons is a human, adult onset, autosomal dominant genetic disorder caused by a mutation in the folliculin (FLCN) gene. It can cause susceptibility to kidney cancer, renal and pulmonary cysts, and noncancerous tumors of the hair follicles, called fibrofolliculomas. The symptoms seen in each family are unique, and can include any combination of the three symptoms. Fibrofolliculomas are the most common manifestation, found on the face and upper trunk in over 80% of people with BHD over the age of 40. Pulmonary cysts are equally common (84%) and 24% of people with BHD eventually experience a collapsed lung. Kidney tumors, both cancerous and benign, occur in 14–34% of people with BHD; the associated kidney cancers are often rare hybrid tumors.
An oncocytoma is a tumor made up of oncocytes, epithelial cells characterized by an excessive amount of mitochondria, resulting in an abundant acidophilic, granular cytoplasm. The cells and the tumor that they compose are often benign but sometimes may be premalignant or malignant.
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.
An adrenal tumor or adrenal mass is any benign or malignant neoplasms of the adrenal gland, several of which are notable for their tendency to overproduce endocrine hormones. Adrenal cancer is the presence of malignant adrenal tumors, and includes neuroblastoma, adrenocortical carcinoma and some adrenal pheochromocytomas. Most adrenal pheochromocytomas and all adrenocortical adenomas are benign tumors, which do not metastasize or invade nearby tissues, but may cause significant health problems by unbalancing hormones.
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. It is generally non-aggressive and amenable to surgical removal, though there is a subtype that is more aggressive and tends to spread to other organs. Congenital mesoblastic nephroma was first named as such in 1967 but was recognized decades before this as fetal renal hamartoma or leiomyomatous renal hamartoma. It is embryologically derived from the metanephrogenic blastema, the same tissue that gives rise to nephroblastomatosis and Wilms tumor.
Salivary gland tumours, also known as mucous gland adenomas or neoplasms, are tumours that form in the tissues of salivary glands. The salivary glands are classified as major or minor. The major salivary glands consist of the parotid, submandibular, and sublingual glands. The minor salivary glands consist of 800 to 1000 small mucus-secreting glands located throughout the lining of the oral cavity. Patients with these types of tumours may be asymptomatic.
A renal oncocytoma is a tumour of the kidney made up of oncocytes, epithelial cells with an excess amount of mitochondria.
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.
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 suspicious for cancer and are commonly removed in a surgical procedure called nephrectomy.
Scrotalultrasound is a medical ultrasound examination of the scrotum. It is used in the evaluation of testicular pain, and can help identify solid masses.
Renal ultrasonography is the examination of one or both kidneys using medical ultrasound.
Ovarian germ cell tumors (OGCTs) are heterogeneous tumors that are derived from the primitive germ cells of the embryonic gonad, which accounts for about 2.6% of all ovarian malignancies. There are four main types of OGCTs, namely dysgerminomas, yolk sac tumor, teratoma, and choriocarcinoma.
Papillary renal cell carcinoma (PRCC) is a malignant, heterogeneous tumor originating from renal tubular epithelial cells of the kidney, which comprises approximately 10-15% of all kidney neoplasms. Based on its morphological features, PRCC can be classified into two main subtypes, which are type 1 (basophilic) and type 2 (eosinophilic).