br Introduction Spinal tumors occur with an

Introduction Spinal tumors occur with an incidence rate of 1.1 per 100,000 persons. Intramedullary spinal tumors comprise approximately 2–4% of all central nervous system neoplasms. The most common kinds of intramedullary tumors are ependymomas, astrocytomas, and hemangioblastomas. Nerve sheath tumors (NSTs) constitute approximately 25% of all tumors arising in the intradural extramedullary space. Approximately 65% of NSTs are schwannomas. Intramedullary spinal schwannomas are rare; since their earliest report in 1931, only 67 cases have been described. They represent 0.3–1.5% of all primary intraspinal tumors, and their preoperative diagnosis based on routine imaging is difficult. Here, we report the case of a patient with intramedullary schwannoma of the cervical spinal cord with histological confirmation and will review the literature with a focus on magnetic resonance imaging (MRI) features. Further, we will discuss the differential diagnosis and pathogenesis of these rare tumors.
Clinical presentation T2-weighted MRI in the sagittal plane showed no significant cyproheptadine hcl manufacturer enhancement at the C3–C4 level of the cervical spinal cord (Fig. 1A), and a well-defined, long, lobulated cystic structure was observed in the central region of C7–T1 in both T1- and T2-weighted images (T1WIs and T2WIs) (Figs. 1B and 1C). Contrast-enhanced T1-weighted MRI revealed an intramedullary lesion with homogeneous enhancement at the C5–C6 level, measuring approximately 3.6 cm in the greatest dimension (Figs. 1D and 1E). An intramedullary tumor of the cervical spinal cord was diagnosed, and the preoperative differential diagnosis included ependymoma, astrocytoma, hemangioblastoma, and metastatic tumor. The patient then underwent total resection of the tumor. A C5–C6 laminectomy was performed with the patient in the sitting position. The dura mater was incised to reveal fusiform enlargement of the spinal cord. A midline dorsal myelotomy was performed, exposing a well-encapsulated reddish tumor, which was easily dissected from the surrounding neural tissue and was entirely removed using an operating microscope. Histopathological findings were consistent with the diagnosis of a benign schwannoma. The postoperative course was uneventful, and the patient was discharged without any change in his neurological status, apart from improvement in the strength of both his upper limbs. Microscopic examination of the specimen revealed a nerve-like tissue with the presence of Verocay body-like structures. Dense areas termed Antoni A (big arrow) and less dense areas termed Antoni B (small arrow) could be observed (Fig. 2A). Immunoperoxidase staining revealed that the tumor cell cytoplasm stained positively for S-100 protein but was negative for glial fibrillary acidic protein (Figs. 2B and 2C).
Discussion Intramedullary spinal schwannomas are rare tumors. Since their earliest report in 1931, only 67 cases have been described worldwide (Table 1). The male:female ratio for intramedullary schwannomas is 1:1; other intramedullary tumors are reported to occur predominantly in men, with a male:female ratio of 3:1. The mean age of incidence of intramedullary schwannoma is approximately 44 years, with the reported youngest and oldest ages of occurrence being 9 and 78 years, respectively. The most commonly affected portion of the spinal cord is the cervical segment (59%), followed by the thoracic (26%) and lumbar segments (15%). Intramedullary spinal schwannomas have a slow growth pattern; therefore, the average interval between the appearance of first symptoms and diagnosis is 36.6 months (range, 1.5 months to 20 years). In only one case, the tumor was incidentally detected, with no neurological symptoms. The pathogenesis of intramedullary schwannomas remains unclear. Several theories have been suggested over the last 50 years, and one of the following mechanisms is considered to be involved in the pathogenesis: MRI features of previous cases of intramedullary spinal cord schwannomas have been published, but have not been described in detail. On T1WIs, the signal intensity obtained for these schwannomas did not differ from those obtained for typical intracanalicular extramedullary schwannomas, and were either isointense or low. A variable signal intensity was observed on T2WIs. No correlations were observed between pathological findings (Antoni type) and MRI signal characteristics. Homogeneous or nodular intense contrast enhancement was seen. According to the current opinions, however, contrast-enhanced images delineate the lesion better and differentiate solid from cystic components, syringomyelia, and edema. Axial images are useful for distinguishing intramedullary from extramedullary lesions.