Renal cell carcinoma refers to a group of different malignancies, each with their own identifiable characteristics, malignant potential and prognosis. Risk factors for tumor growth include cigarette smoking, increased blood pressure, diuretic use, pre-existing renal disease and obesity. Renal cell carcinomas often cause paraneoplastic syndromes such as hypercalcemia (from secretion of parathyroid hormone), increased red blood cells (from release of erythropoietin), hypertension and the rare Stauffer Syndrome (abnormal liver functions despite lack of liver metastasis). Renal cell carcinoma are typically resistant to radiation and chemotherapy, thus surgery tends to be the mainstay of treatment.
Clear Cell Carcinoma
This usually solitary, well-circumscribed tumor is the classic type of renal cell carcinoma and accounts for 65 percent of tumors. They commonly occur in patients with genetic mutations that result in Von Hippel Lindau (VHL) syndrome, which include clear cell carcinoma, pancreatic tumor, pheochromocytoma and retinal angioma, among other tumor growths. They tend to have a golden-yellowish color due to the abundant lipid content of the tumor; tumors that are of a higher grade tend to have decreased lipid content. This is also the most virulent form of renal carcinoma, with the highest metastatic potential (90 percent).
Papillary Renal Carcinoma
These cancers have a genetic basis with trisomy of chromosomes 7 and 17, and can also be acquired through heredity via the mutation of a gene known as MET. They represent between 7 and 14 percent of renal carcinoma and tend to have associated necrosis, which is death of the tumor tissue within the tumor. They have a more favorable prognosis, as they are usually at a low stage when diagnosed; if they reach an advanced stage, they can be as virulent as the clear cell type.
Chromophobe Renal Cancer
These account for between 6 and 11 percent of renal carcinoma, and are usually solitary. They often tend to be quite large at diagnosis and also have a genetic component involved in their development. Chromosomes 1 and Y seem to be the most heavily involved, and tend to be more slow growing and less malignant than its counterparts (10 percent of metastasis).
Medullary Renal Carcinoma
This is a rare type of renal cell carcinoma, and is very aggressive. It is usually seen in those with sickle cell trait, and the chronic sickling of red blood cells in the renal medulla with resultant inflammation is hypothesized to play a role in its development. Genetic components do not seem to play as large of a role in its development like the other types of renal carcinoma.
Collecting Duct Tumor
These are also known as Bellini Duct tumors, and are also rare and very aggressive. They are usually located near the kidney pelvis, which is where the urine drains into the ureters, and as a result blood in the urine (hematuria) is often the initial presenting complaint.
References
- "Cecil Medicine, 23rd Edition;" Goldman; 2007
- "Brenner and Rector's The Kidney, 8th Edition;" Brenner; 2007
- "Urologic Clinics of North America"; Pathologic Features of Renal Cortical Tumors; Tickoo, S., Gopalan, A.; November 2008
