Paragangliiocytoma originates from sympathetic nerve sheath cells, 85%~90% occurs in the adrenal gland, about 10% occurs outside the adrenal gland, such as carotid body, jugular bulb, heart, retroperitoneum, bladder, hepatic portal, thoracic cavity[28–29], Pick named pheochromocytoma that occurred in the adrenal gland in 1912, and named paraganglioma that occurred outside the adrenal gland. There are no accessory ganglia in the normal spinal canal and vertebral body, so the paraganglioma in the spinal canal and vertebral body is very rare, the incidence is about 0.07/1,000,000. The origin of paraganglioma in the spine has not been determined. Some scholars believe that it originated from the sympathetic cells of the lateral spinal cord of the thoracolumbar segment or the ectopic sympathetic trunk branches[30], which mainly occurred in the dura mater of the spinal canal. It is rare to occur in the epidural. Paraganglioma can synthesize, store, and secrete catecholamines. Some tumors have neuroendocrine function. Few cases that occur in the spinal area are accompanied by neuroendocrine function. There are reports in the literature that may be associated with hypertension[31], most of which are concentrated in In the lumbosacral area, cauda equina, and terminal filaments in the spinal canal[32–33], and non-functional tumors account for the vast majority. The prevalence of this disease is about 50 years old. Because most tumors have no functional lesions, non-specific symptoms caused by tumor compression are the first symptoms in clinical practice. Therefore, the misdiagnosis rate and missed diagnosis rate of this disease are extremely high.
MRI is currently the best examination method for the diagnosis of paraganglioma in the spinal canal[34]. It is mainly manifested as soft tissue masses with clear boundaries, T1WI and other signals, T2WI high signals, abundant internal nourishing blood vessels, and a few tumors have spotted hemorrhage, The tumor is obviously strengthened on the enhanced scan, and there are often thick "empty blood vessels" around it, and the enhanced scan shows vascular-like enhancement. Mainly differential diagnosis with neurogenic tumors in the spinal canal, epidermoid cysts in the spinal canal and other rare diseases[35–36]. Hemosiderin deposits can be seen at the edge of the tumor, which is helpful to prompt diagnosis. Hemosiderin deposits are mainly seen in vascular-rich lesions[37]. Preoperative MRI neuroimaging and 3D reconstruction in this patient have important guiding significance for the diagnosis of tumor, the formulation of surgical plan and the recovery of postoperative nerve function.
Pathological examination is the only way to diagnose paraganglioma. The tumor’s main cells are uniform in size, round or almost round, with nuclei located in the center, chromatin punctiform, thinner, and nucleoli are usually inconspicuous. They are distributed in nests and look normal. Paraganglia: Sertoli cells arranged in a single layer around the nest, fusiform or cylindrical, sometimes difficult to identify under light microscope. The nested principal cell and surrounding supporting cells constitute a typical "Zellballen" structure[21]; Immunohistochemistry is mainly used to distinguish it from other neuroendocrine tumors. Chromaffin A (CgA), synapse protein (Syn), neuron-specific enolase (NSE), S-100 protein, glial fibrillary acidic protein (GFAP) and keratin (CK), etc. To a certain degree of diagnostic significance, the expression of Syn, CgA, and NSE among these indicators in this patient was positive.
Total surgical resection is the first choice for treatment of paraganglioma in the spinal canal, and most patients have a good prognosis. The surgery uses the posterior median approach of the vertebral body segment where the tumor is located, and the lamina and dura must be opened. Paraganglioma is located in the subdural epimedullary, mostly closely related to nerve tissue, and has abundant blood supply [38]. Paraganglioma has a rich blood supply and shares a large and deformed blood supply vessel with the conus medullaris. Disconnection of this blood vessel may cause abnormal blood supply to the conus medulla[42]. It is often seen in literature reports that patients have complications such as urinary incontinence after surgery. The possible reasons are not only the damage of the cauda equina during the operation, but also the influence of the blood supply of the conus medullarius after the vessel is broken. Therefore, the blood supply artery should be blocked during surgical resection. In order to reduce bleeding and reduce the tumor volume; the priority is to separate the tumor from the adhering nerve roots, if the nerve roots cannot be separated, then perform a total resection; then strictly stop the bleeding, close the dura mater, and fix the lamina.
Paraganglioma in the spinal canal is a benign tumor, but there are still a few reports of malignant metastasis of the tumor after surgery[39]. Surgery may have a curative effect, but the spread of the tumor limits the chance of radical resection [41]. A small number of tumors that cannot be completely removed may have cerebrospinal fluid dissemination and metastasis. For patients whose tumors are not completely removed, reoperation and combined treatment with radiotherapy and chemotherapy are feasible[33]. According to reports, there are still a few reports that pathological examinations cannot determine the benign and malignant tumors, so long-term follow-up is very important for the prognosis of patients[40]. This patient underwent complete tumor resection during the operation. Thanks to preoperative neuroimaging and 3D reconstruction technology, no important nerves were injured during the operation. The patient’s neurological function recovered well after the operation. The postoperative patient needs to review B-ultrasound, DR, CT, etc. regularly. To better assess the local recurrence. The patient has been followed up for 1 year and 7 months with good internal fixation and no signs of tumor recurrence and metastasis. The follow-up is still ongoing.
Although neuroendocrine markers such as CgA, Syn, S-100 protein, NSE positive and epithelial-derived markers such as CK, EMA and other negative are helpful to distinguish ependymoma, schwannoma, meningioma, chordoma, etc. Pathological examination is still difficult to judge the benign and malignant tumors. It should be judged according to its biological behavior. If lymph node metastasis or/and distant metastasis occurs, it can be considered as malignant paraganglioma. Therefore, long-term follow-up is of great significance in determining the prognosis of patients.