Extrarenal nephroblastomatosis in children: a report of two cases

Abstract

BackgroundExtrarenal nephroblastomatosis is a rare entity which occurs in retroperitoneum and inguinal region predominantly. Here we report two cases of primary extrarenal nephroblastomatosis of Han Chinese in Asian in unusual locations, one is located in testis and paratestis, and the other is paraspinal cord.Case presentationPatient 1 was a 19-month-old boy with a hard and nodular mass adherent to the left testis in inguinal region. Patient 2 was a 9-month-old boy with a 1 × 0.7 × 0.4 cm mass in spinal canal at the midline thoracolumbar region. Histological examinations of the two patients after operations revealed extrarenall nephroblastomatosis with multiple nephrogenic foci, composed of immature glomeruli, tubules and blastemal cells.Then the patients were closely monitored without adjuvant chemotherapy, and has been alive and well without any recurrence for >6 months.ConclusionsMost nephrogenic rests remain subclinical, and thus, complete excision of the lesion with conservative treatment is recommended. Otherwise, nephrogenic rests are close associated with Wilms tumor and regular follow-up is required to ensure early detection of malignant transformation.

Ectopic nephrogenic rests in children: A series of 13 cases in a single institution

“…Approximately 32 cases of pure ENR (30 children and two adults) have been reported, including our three cases . Most of the affected individuals were infants, and several cases were congenital.…”

“…Radiological examinations are not always performed before operations, leading to incidental findings during surgery in some cases; moreover, the radiological image features of pure ENR are seldom described in the literature. The greatest dimension of pure ENR in the literature is usually less than 4 cm, which is relatively smaller than extrarenal nephroblastoma and may be helpful in their differential diagnosis. Lobular contoured, relatively well‐differentiated renal tissues admixed with fibrous tissues and a lack of obvious atypia in histology usually indicate pure ENR.…”

“…Most of the affected individuals were infants, and several cases were congenital. There is a slight male prevalence, with a male‐to‐female ratio of approximately 1.5–1.7:1 . The incidence of pure ENR has not been investigated.…”

“…In our center, pure ENR accounted for about 0.005% of all the surgical specimens from 2004 to present. Common locations include the lumbosacral and sacrococcygeal region, inguinal canal, and testis (approximately 75% of all cases) . Most previously reported cases of pure ENR were associated with malformations, such as spinal dysraphism, lipomeningomyelocele, congenital inguinal hernia, undescended testis, and enteric duplication …”

“…ENR are also known as extrarenal NR, extrarenal nephroblastomatosis, mesonephric remnant, ectopic immature renal tissue, heterotopic NR, hamartoma with primitive renal tissue, and extrarenal nephrogenic blastema . ENR may occur alone (pure ENR) or exist as a part of teratoma (ENR associated with teratoma) and have been reported to occur at the same locations as extrarenal nephroblastoma and teratoma, including the testis, inguinal canal, lumbosacral area, and adrenal gland . Similar to NR in morphology and immunohistochemistry, ENR are considered precursor lesions of extrarenal nephroblastoma.…”