Lumbar canal meningioma of the filum

Case contributed by Ernest Lekgabe


Presented with increasing low back pain radiating to left leg.

Patient Data

Age: 30 years
Gender: Male

Well circumscribed slightly hyperdense intradural tumor at the L5 level. No bone remodeling.

Well circumscribed intradural tumor at the L5 level, predominantly T2w isointense to cord with small cystic components centrally. Predominantly solid homogeneous enhancement. No bone remodeling.


Surgical resection was performed.


Paraffin sections show a moderately cellular tumor with a dural attachment and enclosing fasciculi of myelinated nerve fibers. Tumor cells have uniform round and oval nuclei with vesicular chromatin and a moderate amount of clear, glycogen rich cytoplasm. These are arranged predominantly in solid sheets and lobules.

A vague syncytial arrangement of tumor cells is descernible in several areas. Scattered mitotic figures are identified (2 in 20 HPF).

No areas of necrosis are seen.

Immunohistochemistry shows strong membrane staining in tumor cells for somatostatin receptor 2 (SSR2) and strong nuclear staining for progesterone receptor (PgR). There is strong staining for S-100 protein in incorporated nerve bundles but tumor cells are S-100 negative. No staining for GFAP, cytokeratin CAM5.2, synaptophysin, chromogranin or estrogen receptor (ER) is seen in tumor cells.

The features are of clear cell meningioma (WHO Grade II).


Clear cell meningioma (WHO Grade II).

Case Discussion

Differential diagnoses for this tumor on imaging would include:

  • myxopapillary ependymoma
  • nerve sheath tumor
  • meningioma
  • rarely paraganglioma

Meningiomas are usually more T2w hypointense compared to these other tumors.

Papillary and clear cell meningioma histology are graded as atypical (grade II) meningiomas.

Other features of grade II meningiomas include; increased mitotic figures, high nuclear/cytoplasm ratio, necrosis, patternless growth and prominent nucleoli.

Cell anaplasia and very high mitotic activity are features of malignant meningioma (grade III).

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