Cauda equina neuroendocrine tumor

Case contributed by Frank Gaillard
Diagnosis certain

Presentation

Sciatica.

Patient Data

Age: 30 years
Gender: Male

A well-circumscribed mass below the conus has fairly high T2 signal, intermediate T1 signal and vivid contrast enhancement. No flow voids. No leptomeningeal nodularity or deposits. It is a solitary lesion.

The differential includes myxopapillary ependymoma, paraganglioma or schwannoma.

Case Discussion

The patient went on to have a resection.

Histology

The sections show a well-circumscribed tumor composed of nests and cords of tumor cells amongst a prominent vascular network. The tumor cells are monomorphic with round-oval nuclei and fine-speckled chromatin, and most have an epithelioid appearance. There are vague perivascular pseudo-rosettes. There is no myxoid material or papillary architecture.

By immunohistochemistry, the tumor cells are positive for synaptophysin and chromogranin A, and negative for EMA and GFAP. 5100 and SOX10 highlight scattered single cells. The tumor cells show intact staining for SDHA and SDHB indicating that SDHX mutation is unlikely.

The lesion appears to have been shelled out with very narrow (<0.1mm) but clear margins in the planes examined.

Final diagnosis

paraganglioma of the filum terminale (WHO grade 1) - now known as a cauda equina neuroendocrine tumor.

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