Supratentorial ependymoma

Case contributed by Ralph Nelson
Diagnosis certain

Presentation

Papilledema noted by his optometrist. No history of cancer.

Patient Data

Age: 17 years
Gender: Male
ct

Heterogeous lesion measuring approximately 2.5 x 1.5 x 1.8 cm in the vicinity of the pineal gland with solid slightly hyperdense component and some intrinsic hypodense areas, suggestive of cystic components. A focus of coarse calcification in its superoposterior aspect as well as other tiny suspected microcalcified foci. The lesion is in contact with the superoposterior aspect of the midbrain, tectal plate, as well as the adjacent venous structures. There is associated obstruction of the cerebral aqueduct, resulting to secondary dilatation of the supratentorial ventricular system. There is mild periventricular transependymal edema. 

No midline shift. No other suspicious intra- or extra-axial focal lesion. 

One day later

mri

Redemonstration of a solid-cystic mass in the region of the pineal gland, which is not individualized from the lesion. The lesion measures approximately 2.3 x 1.7 x 1.7 cm, coming in close contact with the confluence of the bilateral internal cerebral veins. The solid component of the lesion follows cortical signal with faint and irregular post-contrast enhancement and restricted diffusion. The lesion blunts the posterior aspect of the third ventricle and extends through the aqueduct, causing obstruction and posterosuperior displacement of the tectal plate.

Moderate secondary dilatation of the ventricular system with mild periventricular transependymal flow. The fourth ventricle is of normal caliber. No significant effacement of the extra-axial CSF spaces.

No midline shift.

No evidence of leptomeningeal nodular enhancement. 

No other intra or extra-axial focal lesion.

Prior to resection, the patient's mass was endoscopically biopsied; results came back inconclusive between an ependymoma and a papillary tumor of the pineal region (PTPR). Subsequently, the mass was partly excised and histopathology then confirmed it to be an “ependymoma, papillary variant, with increased proliferative activity”.

Histology

Microscopic description:

Specimen A: Tiny fragments of grey matter. No tumor.

Specimen B and C: Moderately cellular tumor composed of isomorphic elongated tumor cells with oval euchromatic nuclei arranged in sheets, with perivascular pseudorosettes, occasional true ependymal rosettes, and true papillae covered by polarized ciliated tumor cells. No microvascular proliferation, no necrosis. Approx. 2 mitoses/10 HPF.

Immunophenotype:

  • GFAP: very focally positive in perivascular cell processes
  • EMA: prominent apical staining on surface of true papillae as well as focal dot-like cytoplasmic staining
  • CK8/18: extensive positivity, especially in perivascular cell processes
  • Chromogranin: negative
  • Cyclin D1: weak to moderate nuclear staining in 5-10% of tumor cells
  • Ki67: mostly 10% labeling , but focally up to 20% (estimated) 

Specimen D: Fragments of tumor with severe crush artifact and small fragments of gliotic grey matter.

Diagnosis: Ependymoma, papillary variant, with increased proliferative activity.

The patient went on to receive adjuvant therapy with focal radiation in the form of proton beam therapy, which is recommended over photon beam therapy, for its property of sparing normal tissue.

One mth later post re...

mri

One mth later post resection & endoscopic 3rd ventriculostomy

Expected postsurgical changes related to right parieto-occipital craniotomy.

The surgical bed is clear.

No abnormal signal change or enhancement to suggest recurrence.

Case Discussion

The patient was found to have signs of raised intracranial pressure, an unusual feature for a supratentorial ependymoma, which usually presents with headache, seizures or/and focal neurological deficits.

The imaging findings were typical for an ependymoma: on CT, the mass was isodense relative to gray matter and contained both (micro)calcifications and cystic components. On MRI, the mass's solid component demonstrated isointensity relative to gray matter on T1WI (not shown) and hyperintensity on T2WI with heterogeneous enhancement post-gadolinium.

This patient's histologically confirmed papillary ependymoma did not involve his spinal cord. Ependymoma grading is reported to be less useful, but as per our pathologists, “increased proliferative activity” lesions have been associated with worse outcome.

Supratentorial ependymomas - rare primary tumors of the central nervous system - are thought to arise from the lining of cerebral ventricles or the spinal cord central canal. However, recent studies suggest that radial glial stem cells are the cell of origin. Surgical resection and radiotherapy are the mainstay of treatment. 

So far, one-year post-resection and adjuvant proton radiotherapy, the patient remains free of disease recurrence.

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