Background: Tanycytic ependymomas (TEs) are rare spindle-cell variants of spinal ependymomas. They are classified as central nervous system World Health Organization grade II, and they usually behave like ordinary spinal ependymomas especially following gross total resection (GTR). Case Description: A 43-year-old male presented with a progressive paraparesis and sensory level at T4 (pain/ temperature loss). The magnetic resonance imaging showed an intradural intramedullary tumor extending from Th2 to Th5. Only a subtotal resection was performed as a central portion was tightly adherent to the spinal cord itself. Histology revealed a predominantly grade II TE; the main component showed a low proliferative index, whereas the anaplastic focus had a markedly elevated index. Despite craniospinal tomotherapy (36 Gy), tumor recurred 6 years 7 months later. Local tomotherapy was repeated 3 times (41.4, 40, and 30 Gy), but each treatment produced only transient shrinkage followed by regrowth at shorter intervals. Further irradiation was contraindicated due to cumulative dose constraints. Seventeen years after the first surgery, rapid enlargement over 3 months caused paraplegia and bladder-bowel dysfunction. Reoperation achieved GTR, and at this point the pathology showed a diffuse anaplastic ependymoma; the MR 6 months later showed no tumor recurrence. Conclusion: Although TE is usually indolent, it can harbor an anaplastic subclone and progress to malignancy after subtotal resection. Long-term surveillance and early reoperation when regrowth is first observed should be considered and is likely due to the development of anaplastic features.
Ito et al. (Fri,) studied this question.