Foraminal herniation of a lumbar disc mimicking neurinoma on CT and MR imaging.

A case of a large L3-L4 intervertebral disc herniation causing a widening of the intervertebral foramen is reported. There was a soft-tissue mas within the spinal canal and intervertebral foramen. The soft-tissue mass within the spinal canal and intervertebral foramen showed marked enhancement on magnetic resonance scans after injection of a paramagnetic contrast agent (Gd-DTPA). The combination of lesion configuration and paramagnetic contrast enhancement mimicked a spinal neurinoma. There exists a degree of overlap between the imaging of herniated discs and spinal neurinomas. When this overlap involves several aspects, such as anatomic configuration, mass enhancement, and secondary foraminal dilatation, the differential diagnosis between a herniated disc and a neurinoma may be problematic.