Fig. 2

Hematoxylin and eosin staining of the resected thoracic spine tumor shows metastatic paraganglioma characterized by neuroendocrine cells which occupy the marrow spaces of cancellous bone. The semicircular, hematoxylinophilic curved structure at left represents one of the distorted, calcific bone trabeculae. Occasional foci of hemosiderin are present, consistent with chronic hemorrhage. Immunohistochemical stains of the tumor cells are strongly positive for both synaptophysin and chromogranin, and negative for pancytokeratin and Cam5.2. The Ki-67 proliferation index is elevated at about 20%. The staining pattern is consistent with paraganglioma