intradural lumbar disc herniation was first reported in 1942 , and more than 100 cases have been reported since61420 ) . in cases of intradural disc herniation , surgeons often find it difficult to distinguish between extrusion disc herniation and intradural extramedullary ( idem ) tumors12 ) . this confusion can result in failed surgeries or an incorrect diagnosis of an idem tumor during surgery . in cases of suspected idem tumors , the possibility of intradural disc herniation should be considered if the patient presents with sudden onset back pain and masses located adjacent to a degenerative disc . multiple masses with different enhancement patterns on magnetic resonance images could also confuse surgeons leading to an incorrect diagnosis214 ) . here , we describe an extremely rare case of multiple intradural disc herniations masquerading as multiple idem tumors . a 43-year - old man presented with lower back pain that radiated laterally to his right thigh that had persisted for 3 months . during the previous 6 years , the patient had undergone 3 lumbar spine magnetic resonance imaging ( mri ) examinations and 10 sessions of epidural steroid injection for recurrent back pain . the last of the 3 mri examinations had revealed 3 round intradural masses along the second and third lumbar spine , although there were no specific changes in the disc space compared with the previous magnetic resonance images ( fig . two of the masses were homogeneously enhanced , while the third was nonenhanced ( fig . the nonenhanced mass had moved down within the subarachnoid space , as determined by comparison with the images obtained 7 days previously ( fig . the preoperative diagnosis was multiple idem tumors , possibly schwannoma , and surgery was planned . an l3 partial laminoplastic laminotomy was performed and a durotomy was performed and a durotomy was made , revealing the two enhancing masses . one was a 0.30.5-cm yellowish mass located in the dorsal subarachnoid space at the l2 - 3 disc level and adhered to the cauda equina via vascular proliferation from the nerve roots ( fig . following its separation from the surrounding nerve roots and opening of its capsule - like surface , the mass was removed completely ( fig . a frozen section biopsy confirmed that the mass was composed of degenerated disc material . after careful exploration of the cauda equine , the third mass that was found to be nonenhanced and migrating along the cerebrospinal fluid space on mri was found at the l2/3 level ; it was nonvascular and did not adhere to the cauda equina ( fig . pathological examination of the surgical specimen showed degenerated fibrocartilage , partial capillary proliferation , interstitial edema , and inflammation in parts of the ventral dura mater . because of their numerous and various clinical presentations , preoperative diagnosis of intradural disc herniations is very difficult1716 ) . the most commonly associated symptom is acute exacerbation of back pain , although this is not specific for intradural disc herniation . blikra3 ) observed anatomic adhesions between the posterior longitudinal ligament ( pll ) and dura in a cadaver study . contrast - enhanced mri is the gold standard for the diagnosis of intradural disc herniations78 ) ; however , as in this case , diagnoses are often made during surgery1113 ) . despite this , contrast - enhanced mri is required for the differential diagnosis of spinal idem tumors such as schwannomas or meningiomas1117 ) . rim enhancement is a typical feature of these tumors and is caused by chronic granulation tissue and/or peripheral neovascularization11 ) . in some cases , rim enhancements of the lesion and pll discontinuity were found on gadoliniumenhanced mri4 ) . computed tomography of intradural discs reveal an increased frequency of air densities in the intradural space913 ) . myelography is also useful in detecting complete blockage in 71% of cases of intradural disc herniation1 ) . of note however , similar imaging findings have been noted in cases of other types of disc herniation as well as idem tumors110 ) . obesity ( as in this case ) ; events that rapidly increase intradiscal pressure , such as trauma ; history of treatment for lumbar disc disease ; and dramatic changes in mri findings within a short duration are features more likely to be associated with intradural disc herniation than with idem tumors15 ) . although contrast - enhanced mri is the best modality for diagnosis , in most cases of symptomatic disc herniation , physicians do not have to access to contrast - enhanced mri . in certain cases of intradural disc herniation , extradural extrusion seems like the most logical diagnosis based on mri findings4 ) . in this case , if disc material was not found in the extradural space , most surgeons would conclude that the surgical level of the spine was incorrect . if the vertebral surgical level is correct , surgeons should consider the possibility of an intradural disc herniation and , accordingly , intradural exploration should be conducted . however , it is important to check the rupture point of dura matter before intradural exploration13 ) . the anterolateral portion of the dura matter should be inspected because this is a common route for disc migration into the intradural space . if disc material is found , pathological examination should be performed to confirm the diagnosis . unlike in most cases , we used contrast - enhanced mri to detect 3 masses at different levels with different enhancement patterns . however , the change in position of the nonenhancing mass between the last two mri examinations was an important indicator of a possible intradural disc herniation . we report our experience with an extremely rare case of multiple intradural disc herniations masquerading as multiple idem tumors . even in cases of multiple enhancing idem masses diagnosed preoperatively , surgeons should consider the possibility of intradural disc herniation .
intradural disc herniation is a very rare condition , and multiple intradural disc herniations have not been reported to date . 
 the latter may be confused with intradural extramedullary ( idem ) spinal tumors . here 
 , we report a case of multiple intradural disc herniations masquerading as multiple idem tumors and review the relevant literature . 
 we retrospectively reviewed the patient 's medical chart , reviewed the intraoperative microscopic findings , and reviewed of pubmed articles on intradural disc herniation . 
 the masses considered to be idem tumors were confirmed to be multiple intradural disc herniations . a nonenhancing mass was found to have migrated along the intra - arachnoid space . 
 two enhancing masses could not migrate because of adhesion and showed peripheral neovascularization . 
 we report an extremely rare case of multiple intradural lumbar disc herniations showing diverse enhancing patterns and masquerading as multiple idem tumors . in case of 
 multiple enhancing idem masses suspected preoperatively , surgeons should consider the possibility of intradural disc herniation .