Pigmented intramedullary spinal cord meningioma mimicking a nervous system infection: An unusual report and review of the literature
Correspondence Address: Source of Support: None, Conflict of Interest: None DOI: 10.4103/0028-3886.232293
Source of Support: None, Conflict of Interest: None
An intramedullary spinal cord meningioma is an extremely rare clinical entity, usually derived from persistent arachnoid cell remnants in the spinal coverings. To date, only a few cases have been reported; however, their imaging findings have not been fully described. The diagnosis of an intramedullary spinal cord meningioma is established on the basis of histopathological and immunohistochemical studies. The aim of this study was to describe the characteristics of a patient harboring an intramedullary meningioma. We have also reviewed the previously published literature in order to summarize the characteristic imaging, pathological and immunohistochemistry findings, which currently describe this rare entity.
A 23-year old male patient presented with more than a month's history of recurrent lower limb convulsion accompanied by loss of consciousness for an hour. One month ago, the patient also started feeling numbness in his lower limbs, followed by recurrent episodes of hip pain, and the development of an upward eye gaze paresis and hands clenching, accompanying his lower limb convulsions. During the onset, the patient occasionally had loss of consciousness and nausea, but no incontinence of urine. He was admitted on June 2, 2011.
Neurological examination showed the size of the left pupil being 4 mm and the right pupil being 5 mm. The patient had normal deep tendon reflexes. Cerebrospinal fluid (CSF) examination showed a hemorrhagic CSF with mildly elevated white blood cells, high protein, and low glucose. No bacteria or fungi were found in the CSF culture. The intracranial pressure (ICP) reached 266 mmH2O. The brain computed tomographic (CT) scan revealed an expanded ventricular system. Ventricular puncture and drainage was done twice followed by a lumbar subarachnoid CSF drainage; however, the ICP remained very high.
During the treatment in the hospital, the patient suffered from several episodes of limb convulsions and loss of consciousness several times; convulsions were relieved after administering intravenous diazepam. Sagittal T2-weighted images (T2WI) of magnetic resonance imaging (MRI) showed a high-signal intensity lesion extending from the thoracic 8 to the sacral level [Figure 1]a and [Figure 1]b. Sagittal T1-weighted imaging (T1WI) with gadolinium showed significant enhancement of the lesion from the T8-10 levels, with thickened posterior meninges, as well as the presence of enhancing lesions in the thoracic subarachnoid space [Figure 1]c and [Figure 1]d. There were multiple low-signal lesions at the back of the spinal cord with signs of vascular flow voids being present. The preliminary diagnosis of the patient was thought to be a nervous system infection (most likely tuberculosis) with associated hydrocephalus.
On July 22, 2011, the patient underwent a ventriculoperitoneal shunt; postoperatively, antituberculous and symptomatic treatment were continued. After the institution of treatment, the patient showed a marked improvement, with significantly reduced CSF protein. On August 6, 2011, the patient experienced progressive paralysis and sensory loss of the lower limbs, followed by defecation and urinary difficulties. Spinal MRI confirmed that the spinal cord lesions had increased with more obvious signs of vascular flow void effect [Figure 2] and significant nerve root compression being present, indicating the need for surgical exploration and decompression of the spinal canal.
On August 10, 2011, the patient had thoracic vertebral canal decompression. A thoracic laminectomy from T8-10, followed by opening of the dura, exposed a dark-red intramedullary lesion rich in vascularity. Only a small piece of the tumor was removed for histopathological examination. Histological examination of the lesion specimen showed a pigmented intramedullary spinal cord meningioma (WHO Grade I) [Figure 3]a. Immunohistochemical staining showed positive reactions for epithelial membrane antigen (EMA) [Figure 3]b, human melanoma black 45 (HMB45) [Figure 3]c, and MelanA [Figure 3]d. One month after the surgery, the ICP still remained very high and the patient died.
Meningiomas are among the most common benign tumors of the spinal canal, accounting for approximately 25% of all adult intraspinal tumors. Meningiomas of the spinal canal are typically intradural-extramedullary in location. MRI with gadolinium enhancement assists in their diagnosis. The usual location of spinal canal meningiomas is at the thoracic segment, followed by the cervical segment, and finally, the lumbar segment. Moreover, meningiomas have also been reported in the brain stem. Meningiomas especially occur at the emergence of the sensitive roots in an intradural location, and rarely, also occur in an epidural one. Intramedullary meningiomas are extremely rare, with only a few cases reported in the literature so far. We have reviewed the previously published literature of intramedullary spinal cord meningiomas, and have summarized the characteristic pathological and imaging findings in [Table 1]. Intramedullary meningiomas tend to occur in a younger population than the common intradural meningiomas, which are more common in female patients in an advanced age. Trauma, viral infections, irradiation, and genetic mutations are the possible risk factors responsible for the development of meningiomas.
The pathogenesis of intramedullary meningiomas is unknown and could be explained by the hypothesis that meningocytes are modified fibroblasts derived from mesenchymal cells, and therefore, originate in the mesenchymal cells lining the perivascular spaces of the neuraxis. An intramedullary spinal cord meningioma has no characteristic histological type, and may present as the fibroblastic, transitional, angioblastic, psammomatous, or clear-cell  subtypes. In the present case, the histological examination showed a pigmented meningioma.
The clinical manifestations of these lesions are usually characterized by motor deficits, varying from a slight impairment to complete paralysis, with exaggerated pyramidal signs, sphincteric disturbances, and signs of funicular or radicular impairment. Ordinarily, the symptomatology is restricted to a root or is associated with several sensory and motor neurological deficits. The lower limb convulsion observed in our case were unexplained but occurred most probably due to the associated hydrocephalus and increased ICP as result of arachnoiditis secondary to the presence of the tumor.
MRI is the primary tool for the diagnosis of spinal tumors. Owing to its rarity, the imaging findings of an intramedullary meningioma have not been well characterized. The typical MRI findings of an intramedullary meningioma include a lesion iso-to- hyperintense to the cord on both T1and T2 weighted images (WI). There is a homogenous enhancement seen with gadolinium administration. However, an intramedullary meningioma may even mimic an infectious disease, and therefore, the latter should be considered in the differential diagnosis whenever the characteristic imaging features are revealed on MRI. In our case, the patient was misdiagnosed as having an infectious disease for several months and received antituberculous treatment. The use of a ventricular drainage catheter for a long time may have also led to the infection. The MRI in our case showed multiple low-signal spots at the back of the spinal cord, with signs of a vascular flow void effect. The presence of vascular flow voids could be explained by the compression of the spinal venous drainage by spinal cord lesions, which led to their vasodilation and bleeding. In addition, the lumbar puncture showed the high pressure of CSF; this could also support the presence of venous dilation. The disease duration was so long that the range of lesions expanded and involved both the intramedullary cord substance as well as the meninges, causing secondary meningeal enhancement.
This case needs to be differentiated from vascular malformations, and magnetic resonance angiography (MRA) of the spinal cord could help in this differentiation. When the patient showed deterioration in symptoms despite the administration of anti-tuberculous medication, a thoracic vertebral canal decompression was done. The typical MRI findings of an extramedullary meningioma include an isointense lesion on both T1WI and T2WI, with the occasional presence of dense calcifications; and, a homogenous enhancement seen with gadolinium administration. Moreover, these signs are nonspecific.
Surgery is the treatment of choice in the majority of cases with total resection of the tumors being recommended. Postoperative complications are rare and transitory. However, spinal cord meningiomas have shown the possibility of recurrence even after total resection. Klekamp et al., observed a recurrence of meningiomas in 21% of their cases after 1 year, and in 40.3% after 5 years. A close follow-up is necessary to monitor the recurrence of the tumor. In our case, due to the presence of the intramedullary spinal cord meningioma, the intracranial pressure was high even after a ventriculoperitoneal shunt had been performed. A thoracic vertebral canal decompression and a laminectomy was, therefore, were mandated due to the significant nerve root compression present.
Immunohistochemically, a majority of meningiomas stain positive for EMA and vimentin. However, these are fairly nonspecific markers. Other markers such as cytokeratin (CK), CD68, S100, HMB45, CD34, CD 99, Bcl-2, desmin, carcinoembryonic antigen (CEA), muscle-specific actin, and glial fibrillary acidic protein have been variably observed in meningiomas. In the present case, the tumor cells showed immunopositivity for EMA, HMB45, and MelanA, and immunonegativity for CK, CD68, and desmin, which complied with the diagnosis of a meningioma.
Owing to its rarity, the imaging findings of an intramedullary meningioma have not been well-described so far. The typical MRI findings of intramedullary meningioma include a lesion that is iso-to hyperintense to the cord on both T1WI and T2WI, with homogenous enhancement seen with gadolinium administration. However, an intramedullary meningioma may even mimic the presence of an infectious disease, and therefore, should be considered when uncharacteristic imaging features are revealed on MRI. MRI may also show multiple low-signal spots at the back of the spinal cord with signs of vascular flow void effect due to secondary venous dlilation, as seen in our patient.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
This study was supported by the National Key Clinical Specialties Construction Program of China (No. 2013-544).
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Conflicts of interest
There are no conflicts of interest.
[Figure 1], [Figure 2], [Figure 3]