April 2017

A 57-year-old man with a spinal cord tumor

Ali Aldawood MD, and Kymberly Gyure MD


Patient history:
A 57-year-old man was referred to a physiotherapy center by his primary care physician for evaluation of chronic, intermittent low back pain of 19 months’ duration. He reported that the pain had started after a long international flight. The pain was described as dull and diffuse with radiation to right hip, through the knee, and all the way down to the right heel. His physical examination was significant for a positive straight leg raise test at 45° on the right and at 80° on the left.  No paresthesia or weakness was appreciated. Imaging studies revealed a 3.2 x 1.7 cm, well-circumscribed, contrast-enhancing intramedullary lesion at the L5/S1 vertebral level with prominent cystic degeneration.  The patient was referred for surgical management of this lesion.

Microscopic findings:
Sections from the spinal cord tumor demonstrate a microcystic lesion with intercellular myxoid material and prominent vascular sclerosis (Figure 1).  The tumor cells are relatively monomorphic.


Figure 1.  Monomorphic tumor cells surround sclerotic blood vessels.  Microcystic areas containing myxoid material are also present.  (Hematoxylin-eosin, original magnification 200X)

Diagnosis

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Answer

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Discussion

Myxopapillary ependymoma is a slowly growing glial neoplasm which is almost exclusively located in the regions of the cauda equina, filum terminale, and conus medullaris of the spinal cord, and it is the most common intramedullary neoplasm involving these regions.1,2 Myxopapillary ependymomas have also been reported in other locations such as the thoraco-lumbar spine, subcutaneous tissue, and supratentorial locations (lateral ventricle and cerebrum).3 The lesion is slightly more common in men. It preferentially affects a young age group with an average presenting age of approximately 35 years.3  Myxopapillary ependymoma is believed to arise from the ependymal cells of the spinal canal in the conus medullaris region.1

Typically, the patient will present with a relatively long history of low back pain. This may be associated with lower extremity sensory abnormalities as well as anal and bladder sphincter dysfunction. Imaging studies demonstrate a well-circumscribed lesion with strong post-contrast enhancement.1,2 Rarely, hemorrhagic degeneration or cystic change might be appreciated.2

The external surface of myxopapillary ependymoma is red-brown and smooth.  They have gray-white, mucoid, lobulated cut surfaces with scattered hemorrhage or foci of calcification.1  Their low-magnification appearance is distinctive; cuboidal to columnar tumor cells are radially arranged around hyalinized blood vessels.  Other areas of the tumor consist of microcystic spaces filled with Alcian blue-positive mucin.  Myxopapillary ependymoma is usually diffusely positive for glial fibrillary acidic protein (GFAP), vimentin, and S-100 protein. The Ki-67/MIB1 proliferative index is low, which correlates with the characteristically low mitotic activity of the neoplasm.4  Molecular genetic analysis of these lesions has not revealed any specific findings.  A recent study has classified ependymomas into nine molecular groups across central nervous compartments, and myxopapillary ependymomas are categorized within one group in the spinal compartment.5

Myxopapillary ependymoma is considered a benign, WHO grade I tumor with a generally favorable prognosis; however, higher rates of local failure and central nervous system spread occur in children with these lesions.6,7 Recognizing myxopapillary ependymoma as a distinct entity is important since gross total resection at the time of surgery is a predictive factor for a good clinical outcome.8

References:

  1. McLendon R, Schiffer D, Rosenblum MK, Wiestler OD. Myxopapillary ependymoma.  In:  Louis DN, Ohgaki H, Wiestler OD, Cavenee WK (Eds).  WHO Classification of Tumours of the Central Nervous System, revised 4th edition.  Lyon:  IARC; 2016:104-105.
  1. Gyure KA, Flanagan MB. The central nervous system.  In:  Wick MR, LiVolsi VA, Pfeifer JD, Stelow EB, Wakely PE Jr.  Silverberg’s Principles and Practice of Surgical Pathology and Cytopathology, 5th ed. Cambridge:  Cambridge University Press; 2014:3224.
  1. Weber DC, Wang Y, Miller R, et al. Long-term outcome of patients with spinal myxopapillary ependymoma: treatment results from the MD Anderson Cancer Center and institutions from the Rare Cancer Network. Neuro-oncology 2015;17:588-595.
  1. Prayson RA. Myxopapillary ependymoma:  a clinicopathologic study of 14 cases including MIB-1 and p53 immunoreactivity.  Mod Pathol 1997;10:304-310.
  1. Pajtler KW, Witt H, Sill M, et al. Molecular classification of ependymal tumors across all CNS compartments, histopathological grades, and age groups.  Cancer Cell 2015;27:728-743.
  1. Lucchesi KM, Grant R, Kahle KT, Marks AM, DiLuna ML. Primary spinal myxopapillary ependymoma in the pediatric population: a study from the Surveillance, Epidemiology, and End Results (SEER) database.  J Neurooncol 2016;130:133–140.
  1. Bates JE, Choi G, Milano MT.  Myxopapillary ependymoma: a SEER analysis of epidemiology and outcomes.  J Neurooncol 2016; 129:251–258.
  1. Chen X, Li C, Che X, Chen H, Liu Z. Spinal myxopapillary ependymomas: a retrospective clinical and immunohistochemical study. Acta Neurochir 2016;158:101–107.