The patient went on to have a laminectomy and excision of the tumour.
Histology
MICROSCOPIC DESCRIPTION : The sections show a well circumscribed tumour, with peripheral fibrosis and some evidence of previous haemorrhage. This consists of sheets of cells with a prominent pattern of perivascular pseudorosetting and, due to the prominent arborising vascularity, areas with a nested appearance. Individual tumour cells are polygonal or columnar, the latter morphology particularly associated with blood vessels, with cytoplasm directed towards the vessel and basally located nuclei. The cytoplasm is pale amphophilic. Nuclei are generally rounded with granular or finely vesicular nucleoplasm. Nucleoli, when present, are generally fairly small. Mitoses are seen, at a rate of approximately one per 10 hpf. In places a pseudopapillary appearance is imparted to the tumour by preservation of cells around blood vessels and separation in the intervening areas. In areas, the separation is facilitated by foci of tumour necrosis, interpreted as related to the surgical procedure.
Immunohistochemical stains have been done. The tumour cells are negative for GFAP, S100, CK20, CK7. There is focal staining for chromogranin, with strong staining for synaptophysin. Staining for high molecular weight cytokeratin (CAM 5.2) shows staining of occasional tumour cells. Small numbers of weakly S100 positive cells are present at margins of tumour groups.
The morphologic and immunohistochemical features strongly suggest a neuroendocrine neoplasm. At this location paraganglioma is a significant diagnostic consideration and immunostaining for chromogranin and synaptophysin as well as some staining for cytokeratin would be in accord with this diagnosis. An alternative diagnosis would be metastatic tumour from a neuroendocrine tumour elsewhere in the body, but in view of the radiologic evidence of chronicity of this lesion, that would appear an unlikely proposition (Note: no systemic disease present).