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Paraganglioma of the Central Nervous System (In Ackermann's Surgical Pathology 7ed.)
Primary paragangliomas of the craniospinal axis are virtually restricted to the region of the cauda equina, where they present as delicately encapsulated intradural masses attached to the filum terminale or, less commonly, spinal roots.Afflicted patients are typically in their fifth or sixth decade of life, present with low back pain and sciatica (occasionally accompanied by sensorimotor deficits and incontinence), and are found on myelography to have subarachnoid block. Clinically and radiographically indistinguishable from other neoplasms arising in this location (notably myxopapillary ependymomas and tumors of nerve sheath origin), these functionally silent lesions are histologically, ultrastructurally, and immunophenotypically similar to their extraspinal counterparts. They do, however, manifest a greater tendency to ganglion cell and schwannian differentiation. The designation gangliocytic paraganglioma is sometimes extended to tumors evidencing such features, but these do not constitute a clinically distinctive subset. Occasional variants are characterized by radial perivascular arrays and pseudopapillary structures superficially similar to those of the myxopapillary ependymoma but do not generally elaborate any mucoid matrix and are readily unmasked by their argyrophilia, content of intracytoplasmic dense-core granules, and labeling with antisera to neurofilament proteins, chromogranin, and synaptophysin. Some examples can, in addition, be shown to contain serotonin, somatostatin, and other neuropeptides. A tumor of the cauda equina exhibiting both paraganglionic and ependymal differentiation has been recently described but is clearly exceptional.
With regard to outcome, paragangliomas of the cauda equina are usually amenable to curative resection but may recur and, rarely, kill if inadequately excised. Intraoperative manipulation of such tumors may be complicated by significant elevations of blood pressure and tachycardia, presumably resulting from the release of biogenic amines. One locally aggressive case was reported to exhibit unusual oncocytic features. |
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(Paraganglioma, in Adrenal...)
The gross and microscopic appearance of paragangliomas is practically the same regardless of location and indistinguishable from that of adrenal pheochromocytoma. Well-defined (not so well in the presented case!) nests of cuboidal cells ("Zellballen") are separated by highly vascularized fibrous septa. The individual cells have a moderately abundant granular cytoplasm. As with many other endocrine tumors, bizarre nuclei and vascular invasion are sometimes found. They should not be taken as evidence of malignancy. Mitoses are exceptional.
Immunohistochemically, positivity has been found for neuron-specific enolase, chromogranin, synaptophysin, neurofilaments, opioid peptides, serotonin, somatostatin, and various other peptide hormones. Occasional positivity for keratin has also been encountered. The sustentacular cells can be demonstrated with a stain for S-100 protein, a feature of importance in the differential diagnosis from other endocrine neoplasms. |
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