The patient went on to have a biopsy. At surgery, the dura was opened and the cord resembled a vascular malformation with many very prominent vessels.
Sections show a well-circumscribed tumor composed of abundant small thin-walled capillary sized blood vessels. The intervening stroma contains stellate cells with "bubbly" vacuolated cytoplasm. There is no necrosis, mitoses or atypia seen.
Immunohistochemical results show stromal cells stain: Inhibin+, 8100+ and CAM5.2-; consistent with hemangioblastoma.
The spinal cord, due to its morphology, constrains pathology to a ~10-20 mm cylinder. As such the morphology of lesions is less helpful than in the brain. In this case, the prominent vessels are very helpful in suggesting the diagnosis.