Lumbosacral Wilms' tumor as a component of immature teratoma associated with spinal dysraphism--a rare case and short literature review.

Occurrence of extrarenal Wilms' tumor, in the lumbosacral region, as such or as a component of immature teratoma is an extremely uncommon condition and this diagnosis is almost always postsurgical. We report a case of immature teratoma in the lumbosacral region which was composed of mature teratomatous components and Wilms' tumor as an immature component. This 20-day-old male child presented with a swelling over the lower back at birth. Imaging of the spine revealed spina bifida and tethered cord. Excision of soft tissue swelling and detethering of the cord was performed. This case represents the fourth reported case of lumbosacral Wilms' tumor as a component of immature teratoma associated with spinal dysraphism. We discuss possible mechanisms and clinical characteristics of extrarenal Wilms' tumor and present a short review of the literature.