Due to the increase in ultrasound and CT imaging for nonspecific abdominal complaints,<unk>  masses are frequently incidentally diagnosed on medical imaging. More than 60% of renal cell carcinoma (the most common type of<unk> , are diagnosed incidentally by abdominal imaging for nonspecific abdominal complaints.<unk>  masses can be classified by the nature of the cells in the growth, or by its appearance on radiography. The term<unk>  refers to a malignant tumor, which is an uncontrolled growth of abnormal cells. However,<unk>  masses can be due to growth of normal tissue (benign), inflammatory (a reaction of the immune system), or vascular (cells of the blood vessels). Medical imaging Since there is a large differential diagnosis for a<unk>  tumor, the first step is to characterize the mass with medical imaging to assess its likelihood of being benign or malignant. Ultrasonography is sometimes used to evaluate a suspected<unk>  mass, as it can characterize cystic and solid<unk>  masses without radiation exposure and at relative low cost. Radiologically tumors are grouped based on appearance into simple cystic, complex cystic, or solid. The most important differentiating feature of a<unk> ous and non-cancerous tumor on imaging is enhancement. Simple cysts, which are defined by strict criteria are safe to be monitored if the person does not have any symptoms. However, all masses that are not clearly simple cysts should be further evaluated and confirmed by alternate imaging techniques. Computed tomography (CT) of the abdomen administered with and without IV contrast is the ideal imaging to diagnose and stage<unk> . There is tentative evidence that iodinated contrast agents may cause worsening of<unk>  function in people with chronic<unk>  disease (CKD) with a glomerular filtration rate (GFR) less than 45ml/min/1.73m2 and should therefore be given cautiously in this group. Abdominal magnetic resonance imaging (MRI) is an alternative imaging method that can be used to characterize and stage a<unk>  mass. It may be suggested if contrast material cannot be given. MRI can also evaluate the inferior vena cava if the mass is suspected to extend outside the<unk> . Since the lungs are the most common organ for<unk>  to spread to, a chest X-ray or CT scan may be ordered based on the person's risk for metastatic disease. Histopathologic classification Micrograph of a<unk>  (chromophobe renal cell carcinoma, oncocytic variant), that may be challenging to differentiate from a benign<unk>  tumour (renal oncocytoma). H&E stain. Micrograph of papillary renal cell carcinoma, a form of<unk> . H&E stain. The most common type of<unk>  malignancy is renal cell carcinoma, which is thought to originate from cells in the proximal convoluted tubule of the nephron. Another type of<unk>  although less common, is transitional cell<unk>  (TCC) or urothelial carcinoma of the renal pelvis. The renal pelvis is the part of the<unk>  that collects urine and drains it into a tube called the ureter. The cells that line the renal pelvis are called transitional cells, and are also sometimes called urothelial cells. The transitional/urothelial cells in the renal pelvis are the same type of cells that line the ureter and bladder. For this reason TCC of the renal pelvis is distinct from RCC and is thought to behave more like bladder<unk> . Other rare types of<unk> s that can arise from the urothelial cells of the renal pelvis are squamous cell carcinoma and adenocarcinoma. Other causes of<unk>  include the following: * Sarcoma- for example leiomyosarcoma, liposarcoma, angiosarcoma, clear-cell sarcoma and rhabdomyosarcoma are types of sarcomas that have occurred in the<unk>  * Metastatic tumor from distant organ * Lymphoma * Wilms tumor- an embryonic tumor that is the most common type of<unk>  in children * Carcinoid tumor of the renal pelvis * Carcinosarcoma * Inverted urothelial papilloma- was traditionally regarded as a benign growth. However, there may be an increased risk for recurrence and transformation to TCC. In children, Wilms tumor is the most common type of<unk> . Mesoblastic nephroma, although rare, also typically presents in childhood. Renal cell carcinoma has been further divided into sub-types based on histological features and genetic abnormalities. The 2004 WHO Classification of the Renal Tumors of the Adults describes these categories: * Clear cell RCC * Multilocular clear cell RCC * Papillary RCC * Chromophobe RCC * Carcinoma of the collecting ducts of Bellini * Renal medullary carcinoma * Xp11 translocation carcinomas * Carcinoma associated with neuroblastoma * Mucinous tubular and spindle cell carcinoma * Mixed epithelial stromal tumor Tumors that are considered benign include angiomyolipoma, oncocytoma, reninoma (juxtaglomerular cell tumor), and renal adenoma. Immunohistochemistry + Typical immunohistochemistry for various<unk>  types. PAX8 CD10 CAIX RCC Melanocytic markers Vimentin CK7 HMWCK CD117 / KIT AMACR GATA3 Clear cell RCC + + + (box-like) + - + - - - -/+ - Papillary RCC + + +/- + - + + - - + - Clear cell papillary RCC + - + (cup-like) +/- - + + +/- - - +/- Chromophobe RCC + -/+ - +/- - - + - + - +/- Oncocytoma + -/+ - - - - Focal - + -/+ - Angiomyolipoma - - -/+ - + -/+ - - - - - Collecting duct carcinoma + - -/+ - - + +/- + - - - Tubulocystic carcinoma + + +/- + - +/- -/+ - - +/- - Translocation RCC + +/- -/+ +/- +/- + - - - +/- - MTSCC + -/+ -/+ +/- - + + -/+ - +/- - Legend: * + = usually positive * +/- = frequently positive * -/+ = occasionally positive * - = usually negative Laboratory studies People with suspected<unk>  should also have their<unk>  function evaluated to help determine treatment options. Blood tests to determine<unk>  function include a comprehensive metabolic panel (CMP), a complete blood count (CBC). In addition, these tests help understand the overall health of the person, which can be affected by metastatic disease (disease that is outside of the<unk> . For example, liver or bone involvement could result in abnormal liver enzymes, electrolyte abnormalities, or anemia. A urine sample should also be collected for urinalysis. Biopsy The utility of renal mass biopsy (RMB) lies in that it can confirm malignancy with reliability, can direct therapy based on diagnosis, and can provide drainage. Once imaging has been completed, renal mass biopsy should be considered if there is a high likelihood that the mass is hematologic, metastatic, inflammatory, or infectious. These types of lesions would not be managed surgically, differing from<unk>  originating from the<unk>  originating outside the<unk>  and lymphoma are managed systemically. RMB can accurately diagnose malignancy, however, it cannot reliably diagnose benign disease. In other words, if the biopsy shows<unk> , there is a 99.8% chance that<unk>  is present (Positive Predictive Value= 99.8%). A negative biopsy does not rule out a diagnosis of<unk> . Staging Staging is the process that helps determine the extent and spread of the disease. Renal cell carcinoma is the only type of<unk>  that can be staged. The first step of staging follows the TNM staging system proposed by the Union International Contre le<unk>  that is widely used among<unk> s in other organs. The TNM staging system classifies the primary tumor (T), lymph nodes (N) and distant metastasis (M) of the disease. The American Joint Committee on<unk>  (AJCC) published a<unk>  Staging Manual revision in 2010 that describes the values of TMN for renal cell carcinoma. Lymph node involvement is classified as either regional lymph node metastasis (N1), or no involvement (N0). Similarly, M1 describes distant metastasis, while M0 describes no distant metastasis. The primary tumor of renal cell carcinoma is categorized in the table below, as according to the AJCC 8th Edition<unk>  Staging Manual: Stage TNM Description Tx, N0, M0 Tumor cannot be assessed T0, N0, M0 No evidence of primary tumor I T1, N0, M0 Tumor ≤7 cm; limited to<unk>  T1a, N0, M0 Tumor ≤4 cm; limited to<unk>  T1b, N0, M0 Tumor 4-≤7 cm; limited to<unk>  II T2, N0, M0 Tumor >7 cm; limited to<unk>  T2a, N0, M0 Tumor 7-≤10 cm; limited to<unk>  T2b, N0, M0 Tumor >10 cm; limited to<unk>  III T3, N0, M0 Tumor extends to major veins or perinephric tissue but not into ipsilateral adrenal gland nor beyond Gerota's fascia T3a, N0, M0 Tumor grossly extends into renal vein or its segmental branches, or tumor invades the pelvicalyceal system, or tumor invades perirenal and/or renal sinus fat but not beyond Gerota's fascia T3b, N0, M0 Tumor grossly extends into vena cava below the diaphragm T3c, N0, M0 Tumor grossly extends into vena cava above the diaphragm or invades the wall of the vena cava T1-T3, N1, M0 The main tumor can be any size and may be outside the<unk> , but it has not spread beyond Gerota’s fascia. The<unk>  has spread to regional lymph nodes (N1) but
Kidney cancer
Ureteral cancer
Kidney tumour
Pyonephrosis
Pyelonephritis
Renal cell carcinoma
Liver cancer
Nephritis