Nephrogenic rest within a lipomyelomeningocele in a patient with unilateral renal agenesis

First incidence of extrarenal wilms tumor within the spinal canal in the adult population: a novel case report and literature review

BACKGROUND

Wilms tumor (WT), also known as nephroblastoma, is rare in adults, accounting for merely 3% of all nephroblastomas or 0.2 cases per million individuals. Extrarenal Wilms tumor (ERWT) emerges outside the renal boundaries and comprises 0.5 to 1% of all WT cases, with even rarer incidences in adults. Oncogenic mutations associated with ectopic nephrogenic rests (NR) may contribute to ERWT development. Diagnosis involves surgical resection and pathology examination. Due to scarce cases, adults often rely on pediatric guidelines. We thoroughly searched PubMed, Scopus, and Web of Science databases to establish our case's uniqueness. To the best of our knowledge, this is the first documented incidence of extrarenal Wilms tumor within the spinal canal in the adult population.

CASE PRESENTATION

A 22-year-old woman with a history of congenital lipo-myelomeningocele surgery as an infant presented with a 6-month history of back pain. This pain gradually resulted in limb weakness, paraparesis, and loss of bladder and bowel control. An MRI showed a 6 × 5 × 3 cm spinal canal mass at the L4-S1 level. Consequently, a laminectomy was performed at the L4-L5 level to remove the intramedullary tumor. Post-surgery histopathology and immunohistochemistry confirmed the tumor as ERWT with favorable histology without any teratomatous component.

CONCLUSION

This report underscores the rarity of extrarenal Wilms tumor (ERWT) in adults, challenging conventional assumptions about its typical age of occurrence. It emphasizes the importance of clinical awareness regarding such uncommon cases. Moreover, the co-occurrence of spinal ERWTs and a history of spinal anomalies warrants further investigation.

Nephrogenic rest vs immature teratoma associated with lumbosacral lipomyelomeningocele: a case report and review of the literature

BACKGROUND

Lipomyelomeningoceles (LMMs) are subcutaneous lipomas with dural penetration that often present with spinal cord tethering and may lead to neurological deterioration if untreated. This report describes a rare case of an LMM associated with immature nephroblastic tissue, representing a nephrogenic rest (NR) or, less likely, an immature teratoma.

CLINICAL PRESENTATION

An 8-day-old infant girl presented to the clinic with a sacral dimple. Imaging demonstrated a tethered spinal cord with low-lying conus medullaris and an LMM. A firm mass was noted in the subcutaneous lipoma. Detethering surgery and removal of the lipoma and mass were performed at the age of 6 months. Pathological examination identified the mass as cartilage, fat, and immature nephroblastic tissue consistent with NR tissue or, less likely, a teratoma with renal differentiation.

CONCLUSION

This presentation of an LMM associated with an immature teratoma or NR poses a risk of malignant transformation in patients. As a result, careful surgical dissection, resection, and close clinical follow-up are recommended for these patients.

Myxopapillary ependymoma in children: a study of 11 cases and a comparison with the adult experience

BACKGROUND

Myxopapillary ependymomas (MEPN) are uncommon tumors of the central nervous system, mainly occurring within the conus medullaris-filum terminale. MEPNs can also present in the skin and underlying soft tissues of the sacrococcygeal region. The incidence of extramedullary MEPNs in children is unclear.

PROCEDURE

We retrospectively reviewed our institutional files for MEPN cases between the years 1990-2012. A total of 11 pediatric and 38 adult cases were identified and compared to determine differences between these two distinct age groups.

RESULTS

There were 40 (82%) tumors arising in the spine and nine (18%) in extramedullary sites. Pathologic examination revealed that extramedullary and spinal MEPNs were indistinguishable morphologically and immunophenotypically. Among the 11 children with MEPNs, seven had tumors presenting in extramedullary sites whereas only two adults (5%) had extramedullary tumors; this difference was highly significant (P < 0.0001). The lumbosacral portion of the spinal cord was the primary site for the remaining 40 MEPNs, four (10%) of which presented in children. One extramedullary MEPN (9%) recurred in a 45-year-old woman, and five (11%) of 40 spinal tumors recurred and/or metastasized; two of four children with spinal MEPNs developed recurrences and a manifestation to the aggressive nature of the latter tumor in the spinal cord of children.

CONCLUSIONS

Based upon our experience, MEPN in children is more likely to present in the extramedullary soft tissues of the sacrococcygeal region where its behavior is more indolent than those tumors arising in the spinal cord in children.