What Are the Causes of Kidney Oncocytoma Tumors?

A kidney renal oncocytoma is a benign kidney tumor, though it looks like a renal cell carcinoma (RCC). Unlike an RCC, an oncocytoma is not cancerous. Most cases have no recurrence or mortality, and many have no symptoms. However, because a kidney renal oncocytoma can grow to be quite large and can be confused with an RCC, removing a kidney is the typical treatment.

Causes

• Kidney Oncocytoma's have a dense accumulation of mitochondria (the energy powerhouse of the cell). Unfortunately, the cause of this is unknown. They are most frequently found in patients with Birt-Hogg-Dube Syndrome, a disease characterized by benign tumors of the hair follicle, skin, and kidney.

Identification

• Men are more likely to have a kidney oncocytoma than women, at a rate of two or three to one. This benign tumor is also likely to appear in patients aged 62 to 68 years old. The tumors are about the size and shape of a peach (7cm). When dissected, they are mahogany in color and granulated, with a central scar that is fleshy. In less than 10 percent of the cases, an RCC is also present with an oncocytoma.

Rare

• Most often, a renal tumor is not an oncocytoma. In fact, only three to 7 percent of renal tumors are. With less than 200,000 Americans diagnosed with a renal oncocytoma, the Office of Rare Diseases of the NIH lists it as a rare disease.

Symptoms

• Even when large, the tumor is often asymptomatic and is discovered during an examination for something else. In less than a fifth of all cases, symptoms will be present. These include flank pain, blood in the urine, and an abdominal mass. Blood in the urine is the most likely one to appear.

Treatment

• Treatment is usually a total or partial nephrectomy (kidney removal). It is too risky to rely on biopsies, since these have only met with variable success. Differentiating RCC from oncocytomas with percutaneous renal biopsy, fine needle spiration cytology, or frozen section biopsy, has been so inconsistent that it is agreed the securest treatment option is to remove the kidney. The National Institute of Health calls the nephrectomy the only reliable means to have a definitive diagnosis and treatment.

Prognosis

• In a partial nephrectomy, only the tumor and any damaged tissue is removed from the kidney. A radical nephrectomy results in the removal of the kidney, the ureter which leads to the bladder, the adrenal gland, and the surrounding fatty tissue. With nephrectomy, the prognosis is excellent.