Click Image to Enlarge.
What is Wilms' Tumor?
Wilms' tumor is a very rare form of kidney cancer that occurs in young children, usually between the ages of two and five. The kidneys are two fist-sized, bean-shaped organs in the back of the torso, just above the waist. The kidneys filter waste and excess water from the blood and turn it into urine. The kidneys begin developing in the fetus before birth. After birth, immature cells in the kidneys continue to mature and develop during the first few years of life. In children with Wilms' tumor, these immature cells mutate and begin to grow rapidly and uncontrollably. Wilms' tumor usually develops in a single kidney, but some Wilms' tumor patients may have multiple tumors in the same kidney or tumors in both kidneys. Wilms' tumor is usually fairly aggressive, and can grow very large very quickly, but doctors can cure Wilms' tumor in 90% of cases.
Wilms' tumor is classified into two groups, depending on how the cells look under a microscope:
-
Favorable histology
Over 90% of Wilms' tumors have a favorable histology, meaning the cancer cells are abnormal, but not too different from normal cells. These tumors generally have a good prognosis, respond well to chemotherapy, and have a good chance of being cured.
-
Unfavorable histology (anaplastic Wilms' tumor)
In rare cases, Wilms' tumor may have an unfavorable histology, meaning the cancer cells look very different from normal cells under a microscope. The appearance of these cells may vary widely, and they may have very large and deformed nuclei. These cells divide much more rapidly than Wilms' tumors with favorable histology, making these tumors harder to treat.
