Program Nr: 581 for the 2006 ASHG Annual Meeting

Multiple perineural thoracic cysts presenting as "neurofibromas". K. Gardner1, J. Boardman2. 1) Veterans Administration Pittsburgh Healthcare System, Dept Neurology, Univ Pittsburgh, Pittsburgh, PA; 2) Dept of Neuroradiology, Univ Pittsburgh, Pittsburgh, PA.
   We report a case of isolated perineural cysts found along multiple, bilateral thoracic spinal nerve roots that were initially thought to represent neurofibromas. No other conditions associated with dural ectasia / perineural cysts were identified. Localized congenital and post-traumatic or surgical perineural cysts have been described previously though never involving multiple levels as in the case presented here. Incidental "Tarlov" cysts have been described primarily in lumbosacral levels though the frequency of these is quite low according to a recent large sampling of lumbosacral MRI images (1.5%).Dural ectasia, arachnoid, and perineural dilation around multiple spinal roots can also be associated with Neurofibromatosis-1 (NF1) or with Marfan Syndrome. Dural ectasia is one of the major diagnostic criteria for Marfan Syndrome using Ghent nosology, also found usually in lumbo-sacral regions. With NF1 perineural cysts and dural ectasia can occur at any spinal level, are associated with other clinical features for NF1, and are sometimes associated with plexiform spinal neurofibromas. Careful evaluation of MRI imaging signal characteristics is critical to first differentiate cysts from tumors in patients presenting with thickened spinal nerve sheaths. T2 signal should match CSF signal for perineural cysts and T1 signal should match that of nerve root in the case of tumor expansion of nerve sheath (with or without enhancement). Those found to have perineural cysts without enlargement of nerve roots should then be examined carefully to exclude associated conditions looking for stigmata of Neurofibromatosis-1 (NF1) and for connective tissue disorders such as Marfan Syndrome. If thickened nerve roots are truly present then the differential for paraspinous tumor includes NF1, NF2, and schwannomatosis depending on presence or absence of characteristic skin findings, vestibular schwannomas, and other diagnostic features.