The patient went on to have a laminectomy and excision of the mass.
Histology
Macroscopic Description: Specimen A is received in a single container and description "intradural tumour of cauda equina" and consists of resection of a smooth red-brown lesion measuring 4 x 2 x 1.5 cm.
Microscopic Description: Sections show a circumscribed, highly vascular neoplasm composed of in some areas of tumor cells arranged in between fibrovascular septate. In most areas, the cells are arranged around thickened, hyalinized blood vessels. Both medium and large diameter blood vessels are seen within the lesion. The tumor cells have round to ovoid vesicular nuclei with a "salt and pepper"- like chromatin pattern with inconspicuous nucleoli. The cells have moderate amounts of granular eosinophilic cytoplasm. There is evidence of both acute and chronic hemorrhage. Mitotic figures are rare. Reticulin stain highlights the extensive vascularity of the lesion but there are nests of tumor cells devoid of reticulin production. The tumor is immunonegative for GFAP and strongly and diffusely immunopositive for synaptophysin. There is focal cytoplasmic expression of chromogranin. Only scattered cells are immunopositive for S100. In addition, S100 immuno-positivity is also seen in fine processes within the tumor. MIB1 labelling shows only scattered positive cells.
FINAL DIAGNOSIS: paraganglioma of the cauda equina.