Lumbar canal meningioma of the filum

Case contributed by Dr Ernest Lekgabe

Presentation

Presented with increasing low back pain radiating to left leg.

Patient Data

Age: 30 years
Gender: Male

Well circumscribed slightly hyperdense intradural tumour at the L5 level. No bone remodelling.

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

Pathology

Surgical resection was performed.

MICROSCOPIC DESCRIPTION:

Paraffin sections show a moderately cellular tumour with a dural attachment and enclosing fasciculi of myelinated nerve fibres. Tumour 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 tumour 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 tumour 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 tumour cells are S-100 negative. No staining for GFAP, cytokeratin CAM5.2, synaptophysin, chromogranin or oestrogen receptor (ER) is seen in tumour cells.

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

DIAGNOSIS:

Clear cell meningioma (WHO Grade II).

Case Discussion

Differential diagnoses for this tumour on imaging would include:

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

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

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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Case information

rID: 56178
Case created: 16th Oct 2017
Last edited: 17th Nov 2017
System: Spine
Inclusion in quiz mode: Included

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