Pacinioma of the cauda equina.

Lesions composed of Pacinian corpuscles or showing Pacinian corpuscle differentiation have usually been described in relation to benign tumours of the peripheral nervous system or reactive hyperplastic processes. On the other hand, mature Pacinian corpuscles have occasionally been detected as part of intraspinal lumbosacral lipomas, a rare developmental anomaly usually associated with spina bifida. A lesion of the cauda equina composed of numerous mature Pacinian corpuscles and nerve fascicles embedded in adipose tissue in association with spina bifida occulta is described in a 5-month-old male with a sacral red papula. Magnetic resonance imaging (MRI) revealed a cord-like mass in the region of the cauda equina, presumably connected to the subcutis. With the exception of a low lying, tethered spinal cord, there was no neurological deficit and the range of motor development was normal. In March 2005, at 17 months, surgery was carried out. A cord of yellow tissue was found running from the subcutis through the bone defect into the lumbosacral spinal canal. Intradurally, it ran parallel to the cauda equina, terminating at the conus medullaris. Fifteen months after the surgery the development of the child was normal. Only two similar cases have been reported so far. Due to their occurrence in the sacrococcygeal region and association with developmental anomalies, they have been regarded as malformations and the term Pacinioma has been suggested. Our case with clusters of Pacinian corpuscles may represent a rare variant of complex intraspinal lumbosacral lipomas, closely related to Paciniomas reported by Bale.