CNS & pituitary tumors

Gliomas, glioneuronal tumors, and neuronal tumors

Ependymal tumors

Myxopapillary ependymoma



Last author update: 6 April 2023
Last staff update: 6 April 2023

Copyright: 2002-2024, PathologyOutlines.com, Inc.

PubMed Search: Myxopapillary ependymoma

Zubair Ahmad, M.B.B.S.
Aisha Memon, M.B.B.S.
Page views in 2023: 15,405
Page views in 2024 to date: 5,696
Cite this page: Ahmad Z, Minhas MK, Memon A. Myxopapillary ependymoma. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/cnstumormyxopapillaryependymoma.html. Accessed May 19th, 2024.
Definition / general
  • CNS WHO grade 2 glial neoplasm with a variably papillary architecture characterized by a radial arrangement of spindled or epithelioid to cuboidal cells around blood vessels with perivascular myxoid change (intermediate layer of Alcian blue positive myxoid stroma) and mucin rich microcyst formation (Neuro Oncol 2021;23:1231)
Essential features
  • Glioma with papillary architecture and perivascular myxoid change or at least focal myxoid microcysts
  • Immunoreactive for glial fibrillary acidic protein (GFAP)
  • For unresolved tumors, DNA methylation profile is aligned with myxopapillary ependymoma
ICD coding
  • ICD-O: 9394/1 - myxopapillary ependymoma
  • ICD-11: 2A00.0Y & XH15U1 - other specified gliomas of brain & myxopapillary ependymoma
Epidemiology
Sites
Pathophysiology
Etiology
  • Unknown
Clinical features
  • Chronic lower backache
  • Sciatica
  • Sensory or motor deficits leading to impotence, urinary and fecal incontinence, myelopathy
Diagnosis
Radiology description
  • Well circumscribed, sharply demarcated, ovoid, contrast enhancing mass in the cauda equina / conus / filum terminale region
  • Hyperintense on T1 and T2 weighted MRI with intense contrast enhancement
Radiology images

Contributed by Ahmed Ijaz Gilani, M.B.B.S., M.D., Ph.D.
MRI T1 with contrast

MRI T1 with contrast

MRI T2

MRI T2

Prognostic factors
  • Relatively favorable prognosis with 10 year survival rates > 90.6% (J Neurooncol 2016;126:165, Neuro Oncol 2015;17:588)
  • Often resistant to complete removal due to locally advanced growth or cerebrospinal fluid borne seeding of the thecal sac or more rostral neuroaxis; this may be seen in > 50% of pediatric cases (World Neurosurg 2020;136:e245, J Neurooncol 2016;126:165)
  • Many patients live with this disease but require repeated operations and adjuvant therapy
  • Tumors arising in the conus have a poorer prognosis than tumors in the cauda equina as the former adhere strongly to the spinal cord and are less amenable to resection
  • Radiotherapy improves progression free survival (Neuro Oncol 2015;17:588)
  • Anaplastic histology may increase risk of aggressive behavior (Brain Pathol 2019;29:75)
Case reports
Treatment
  • Surgical excision is the mainstay of treatment
  • Often lifted cleanly from the operative bed; others dissected piecemeal but still in toto
    • Low risk of recurrence in either of the above scenarios
  • Radiotherapy reserved for subtotally resected tumors
  • Some authors recommend radiotherapy for tumors excised completely but piecemeal (Mod Pathol 1997;10:304, Neurosurgery 1992;30:202, Cancer 1985;56:883)
Gross description
  • Often encapsulated, soft in consistency, pink to tan-gray
  • May be grossly gelatinous or show hemorrhage and cystic changes
Gross images

Contributed by Moneil Patel, M.D. (Case #111)
On telfa pad

On telfa pad

Frozen section description
  • Intraoperative squash / smear preparation and frozen section reveals epithelioid to spindled tumor cells arranged around microcysts and forming papillary structures with perivascular myxoid change; these features are diagnostic in the appropriate clinical setting
Microscopic (histologic) description
  • Most common pattern is radial arrangement of cuboidal to epithelioid elongated glial tumor cells around hyalinized fibrovascular (central, often hyalinized blood vessels) cores in a papillary configuration
  • Accumulation of basophilic myxoid material around blood vessels (myxoid stroma) and in microcysts
  • Myxoid material is highlighted by PAS and Alcian blue positive staining
  • In cases composed of confluent sheets of epithelioid cells with little or no papillary structures, PAS and Alcian blue positivity is useful in reaching a correct diagnosis
  • Fascicular growth and spindle cells are common
  • Pleomorphic tumor giant cells can be seen
  • Occasionally tumor cells show distinctive eosinophilic balloons; these are PAS positive spherules that demonstrate spiculated reticulin staining (Am J Surg Pathol 1996;20:1091)
  • Uncommon examples reported as anaplastic myxopapillary ependymomas show hypercellularity and reduced mucin in association with at least 2 of the following features: ≥ 5 mitoses / 10 high power field, Ki67 labeling index ≥ 10%, microvascular proliferation, spontaneous necrosis (Brain Pathol 2019;29:75)
Microscopic (histologic) images

Contributed by Ahmed Ijaz Gilani, M.B.B.S., M.D., Ph.D. and Aisha Hassan Memon, M.B.B.S.
Radial arrangement

Radial arrangement

Epithelioid tumor cells

Epithelioid tumor cells

Papillary structures

Papillary structures

Microcystic pattern

Microcystic pattern

Hyalinized fibrovascular core with myxoid matrix

Hyalinized fibrovascular core with myxoid matrix


Alcian blue

Alcian blue

GFAP

GFAP

Olig2

Olig2

EMA

EMA

Ki67

Ki67

Cytology description
  • Cytology usually recapitulates the histologic findings; myxoid matrix and cells show nuclear uniformity and process formation
  • Epithelioid to spindle cells
  • Arrangement of tumor cells around blood vessels forms papillary structures with perivascular myxoid change
  • Tumor cells are arranged around myxoid microcysts
Cytology images

Contributed by Ahmed Ijaz Gilani, M.B.B.S., M.D., Ph.D. and Brittany Pakalniskis, M.D. (Case #399)
Stromal globules

Stromal globules

Papillary structures and rosettes

Papillary structures and rosettes

Stromal globules (Diff-Quik stain) Stromal globules (Diff-Quik stain)

Stromal globules (Diff-Quik stain)

Stromal globules (Pap stain) Stromal globules (Pap stain)

Stromal globules (Pap stain)

Positive stains
Negative stains
Electron microscopy description
  • Zipper-like intercellular junctional complexes, occasional cilia, surface and intraluminal microvilli are typical features of ependymal differentiation
  • In addition, interdigitating cell processes and microtubular aggregates bond by endoplasmic reticulum
Molecular / cytogenetics description
  • Unique DNA methylation profile (however, histologically classic ependymomas may also cluster on DNA methylation with myxopapillary ependymomas)
  • Prognostic significance of DNA methylation profile of myxopapillary ependymomas in context of uncharacteristic histological features (little myxoid change, pseudorosetting, spindle cells or tanycytic features) is not known
  • Recurrent gain of chromosome 16 and losses of chromosome 10 have been noted (Acta Neuropathol 2020;139:305, Cancer Cell 2015;27:728, Neuro Oncol 2018;20:1616)
Sample pathology report
  • Lower spinal mass, resection specimen:
    • Myxopapillary ependymoma, CNS WHO grade 2
Differential diagnosis
  • Schwannoma:
    • Arises from nerve roots (myxopapillary ependymomas usually arise in the filum terminale)
    • Usually, distinctive histological appearance from ependymoma; however, a paucicellular ependymoma with fascicular architecture may simulate schwannoma
    • No Antoni A or B areas are present in ependymomas
    • There are no nuclear or cytoplasmic inclusions in ependymomas
    • Myxopapillary ependymomas have a delicate rather than densely collagenized capsule seen in schwannomas
    • Schwannomas show pericellular reticulin and extensive immunostaining for laminin and type IV collagen
    • Both tumors are S100 and GFAP positive
    • Schwannomas show more intense staining for S100 compared with GFAP; the reverse is true for myxopapillary ependymomas
  • Paraganglioma:
    • More often arises from nerve roots than ependymomas
    • Presence of zellballen pattern or ganglion cells confirms the diagnosis of paraganglioma
    • Chromogranin positive (myxopapillary ependymomas are negative)
  • Chordoma:
    • Mostly extradural
    • Mucinous matrix of myxopapillary ependymoma may simulate chordoma; however, mucin distribution in chordoma is diffuse and tends not to be confined in perivascular spaces
    • Chordomas are strongly immunoreactive for low molecular weight keratins and EMA; negative for GFAP
  • Metastatic adenocarcinoma:
    • Glandular differentiation, goblet or signet cells with intracytoplasmic mucin supports the diagnosis of metastatic adenocarcinoma
    • Metastatic carcinomas are keratin positive and GFAP negative
  • Myxoid chondrosarcoma:
    • Myxoid or chondroid matrix with lacunar-like spaces supports the diagnosis of myxoid chondrosarcoma
    • Myxoid chondrosarcoma cells would be negative for GFAP
Board review style question #1
A 22 year old man was diagnosed with a myxopapillary ependymoma in the filum terminale of the spinal cord. The diagnosis was confirmed by histological examination and immunohistochemical staining. What is the most important IHC stain expressed by this tumor that distinguishes it from the other lesions included in the differential diagnosis?

  1. CD99
  2. GFAP
  3. Keratin
  4. Olig2
  5. S100
Board review style answer #1
B. GFAP. Diffuse immunoreactivity for GFAP distinguishes myxopapillary ependymoma from metastatic carcinoma, paraganglioma, schwannoma, chordoma and myxoid chondrosarcoma (Appl Immunohistochem Mol Morphol 2013;21:485).

Comment Here

Reference: Myxopapillary ependymoma
Board review style question #2

In the 5th edition of the 2021 WHO classification for CNS, which histological grade does myxopapillary ependymoma correspond to?

  1. Grade 1
  2. Grade 2
  3. Grade 3
  4. Grade 4
  5. Unassigned
Board review style answer #2
B. Grade 2. The Consortium to Inform Molecular and Practical Approaches to CNS Tumor Taxonomy update 6 recommends that spinal myxopapillary ependymomas be diagnosed based on histological criteria but notes that these tumors have a clinical outcome similar to classic ependymoma and should be assigned WHO grade 2 rather than grade 1 assigned in 2016 WHO CNS (Brain Pathol 2020;30:844).

Comment Here

Reference: Myxopapillary ependymoma
Back to top
Image 01 Image 02