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Nephroblastomatosis refers to multiple or diffuse rests of nephrogenic tissue. They are persistent embryonal remnants in the kidney that are apparent precursors to Wilms tumor.
The involved kidneys are typically enlarged and have a lobulated configuration. US, CT, and MRI can be used to identify and monitor nephroblastomatosis.
The following are several conditions in which children may have nephroblastomatosis and can develop Wilms tumor:
- Drash syndrome (pseudohermaphroditism),
- aniridia, and
- a positive family history of Wilms tumor or nephroblastomatosis.
What are the two major types of nephroblastomatosis?
Perilobar and intralobar are the two major types of nephroblastomatosis. The perilobar form is limited to the periphery of the kidney, whereas the intralobar form can be found anywhere within a renal lobe and within the renal pelvis and collecting system. Nephroblastomatosis may remain dormant, mature, involute, develop hyperplastic overgrowth, or become neoplastic (Wilms tumor).
How can nephroblastomatosis be distinguished from Wilms tumor?
Generally, Wilms tumor is suspected when a lesion noted by either US or CT is greater than 3 cm and has a spherical configuration. Many lesions previously thought to be small or medium-sized Wilms tumors, especially in cases of bilateral or multicentric tumor, may represent hyperplastic nephroblastomatosis. Biopsy is of limited value in distinguishing the hyperplastic form from Wilms tumor, and serial imaging is crucial in determining whether surgery should be performed. Wilms tumor is the most common childhood abdominal malignancy.