Diffuse hyperplastic perilobar nephroblastomatosis.

Nephroblastomatosis is a rare preneoplastic lesion defined as the presence of diffuse or multifocal nephrogenic rests. They are divided into 4 categories: perilobar, intralobar, combined, and universal. The aim of this report is to describe a case of diffuse hyperplastic perilobar nephroblastomatosis. A 1-year-old boy presented with an abdominal mass on the left side. Computed tomography scan showed a homogeneous, isointense enlarged left kidney. A fine needle aspiration cytology was reported as Wilms tumor. After chemotherapy, the left kidney was excised. Nephrectomy specimen presented a thick cortical rim of hyperplastic nephrogenic tissue, well delineated from preserved renal parenchyma without pseudocapsule. Nephroblastomatosis is a rare condition affecting renal parenchyma. Diagnosis is based on imaging studies, such as ultrasound, computed tomography scan, and magnetic resonance imaging. Fine needle aspiration cytology is of limited value. Therapeutic management is controversial. Chemotherapy is used preoperatively, and surgical excision may be an alternative for refractory cases.