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|Year : 2022 | Volume
| Issue : 8 | Page : 206-210
Adult Intramedullary Pilocytic Astrocytomas: Clinical Features, Management, and Outcomes
Tao Yang1, HaiBo Wu2, ChengYu Xia1
1 Department of Neurosurgery, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui, China
2 Department of Neuropathology, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui, China
|Date of Submission||19-Sep-2018|
|Date of Decision||16-Nov-2019|
|Date of Acceptance||20-Mar-2020|
|Date of Web Publication||11-Nov-2022|
Department of Neurosurgery, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, 17 Lujiang Road, 230001, Hefei
Source of Support: None, Conflict of Interest: None
Purpose: Adult intramedullary pilocytic astrocytomas (PAs) are exceedingly rare. The aim of this study was to summarize our experiences in treating adult intramedullary PAs.
Materials and Methods: We retrospectively reviewed the records of seven adult patients who underwent microsurgery for intramedullary PAs between 2010 and 2017. Magnetic resonance imaging was the standard radiological investigation. The diagnosis of PAs was based on pathology. All the follow-up data were obtained during office visits.
Results: There were three males and four females with the mean age of 40.9 years. The tumors generally exhibited hypointensity on T1-weighted images (WI) and hyperintensity on T2WI. Contrast-enhanced T1WI showed heterogeneous enhancement. Gross total resection (GTR) of the tumor was achieved in four cases and subtotal resection (STR) was achieved in three cases. Two cases of STR received postoperative radiotherapy. One STR case had mildly residual tumor regrowth. At the last follow-up, neurological status was improved in six patients.
Conclusion: The accurate diagnosis of adult intramedullary PAs depends on pathology. GTR is the best treatment and the outcome is favorable. STR increases the risk of tumor recurrence, and regular follow-up is necessary. Due to uncertain therapeutic efficacy, radiotherapy should be considered carefully for cases of STR.
Keywords: Adult, intramedullary, pilocytic astrocytoma, spinal cord tumor, treatment options
- The accurate diagnosis of adult intramedullary PAs depends on pathology.
- GTR is the best treatment.
- Radiotherapy should be considered carefully for cases of STR.
|How to cite this article:|
Yang T, Wu H, Xia C. Adult Intramedullary Pilocytic Astrocytomas: Clinical Features, Management, and Outcomes. Neurol India 2022;70, Suppl S2:206-10
Pilocytic astrocytomas (PAs) are generally considered as benign entities with slow-growing nature, histologically corresponding to WHO grade I and can be found in the entire neuraxis, including cerebellum, thalamus, and optic pathway.,, However, intramedullary PAs are infrequent, and most of them occur in the pediatric population.,,,,,,,,, Due to the extremely low morbidity rate, there are few reports of adult intramedullary PAs in the literature.,,,,,,,, In addition, many cases were reported together with other low-grade gliomas and limited clinical data were provided.,,, In this article, we summarize our surgical experience with adult patients with intramedullary PAs in a single institution.
| » Materials and Methods|| |
This retrospective study enrolled seven adult patients with intramedullary PAs who underwent surgery from 2010 to 2017. Pre- and postoperative magnetic resonance imaging (MRI) with gadolinium-contrast enhancement was performed in all patients. Clinical data were obtained through chart review including demographics, imaging data, surgical notes, and pathological reports. The study was approved by the institutional review board of the First Affiliated Hospital of USTC.
All patients underwent surgery through a posterior approach with intraoperative monitoring of somatosensory and motor-evoked potentials, and no evoked potentials were lost during the surgery. Follow-up data for all patients were obtained during office visits. The individual's neurological status was evaluated according to the Modified McCormick grade [Table 1]. This assessment was performed before surgery, at discharge, at 3 months after surgery and annually thereafter.
| » Results|| |
There were three males and four females with the mean age of 40.9 years (range: 22–58 years). The mean duration of symptoms was 21.5 months (range: 2 weeks–72 months). The symptoms included motor disorders, sensory disorders, sphincter dysfunction, and pain [Table 2]. Based on T1-weighted images (WI), the tumors had hypointensity in six cases and isointensity in one case. T2WI revealed hyperintensity in five cases and mixed intensity in two cases. Heterogeneous enhancement was observed on contrast-enhanced T1WI in all cases. Peritumoral syringomyelia appeared in one case (14.3%). Gross total resection (GTR) was achieved in four cases, and subtotal resection (STR) was achieved in three cases with an ill-defined margin of the tumor. Two cases of STR underwent postoperative local radiation therapy (45 Gy in 25 fractions). During a mean follow-up period of 45.9 months, no tumor recurrence occurred in six patients. However, one STR case had mildly residual tumor regrowth. At the last follow-up, neurological status had markedly improved in six patients and remained stable in one patient.
|Table 2: Summary of seven adult patients with intramedullary pilocytic astrocytomas|
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A 49-year-old woman was admitted with weakness and numbness of the right upper limb for 18 months' duration. MRI revealed an intramedullary lesion located eccentrically in the right spinal cord at C2–C4 levels. The lesion showed hypointensity on T1WI and hyperintensity on T2WI. Heterogeneous enhancement was observed on the contrast-enhanced T1WI [Figure 1]. The preoperative diagnosis was astrocytoma. The patient had a cervical laminectomy. After opening the dura mater, a midline dorsal myelotomy was performed on the swollen spinal cord. The tumor was red-grayish, rubbery, and with moderate vascularity [Figure 2]. Ultrasound aspiration was used to excavate the tumor from the inside outward until its interface with the white matter was reached. GTR was achieved with intraoperative monitoring of somatosensory and motor-evoked potentials [Figure 2]. Histopathological sections revealed a PA composed of a fibrillar background, elongated astrocytic tumor cells, Rosenthal fibers, and eosinophilic granular bodies [Figure 3]. There was no evidence of necrosis, mitotic activity, or other malignant features. Immunohistochemical examination showed that the tumor cells were positive for glial fibrillary acidic protein (GFAP) and S–100 protein [Figure 4] and [Figure 5]. The postoperative course was uneventful. The patient did not receive radiotherapy and was discharged 14 days after surgery. At the follow-up examination 17 months after the operation, she had a significant improvement of weakness and numbness of the right upper limb. The MRI showed no evidence of tumor recurrence [Figure 6].
|Figure 1: The lesion was hypointense on T1-weighted image (WI) (a) and hyperintense on T2WI (b); heterogeneous enhancement observed on the contrast-enhanced T1WI (c); axial contrast-enhanced T1WI demonstrating the lesion grew eccentrically within the spinal cord (d)|
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|Figure 2: After myelotomy was performed, a red-grayish, rubbery lesion exposed in the intramedullary space (a); intraoperative finding after surgery showing total resection of tumor (b)|
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|Figure 3: Pathological specimen: a fibrillar background, elongated astrocytic tumor cells, Rosenthal fibers, and eosinophilic granular bodies (hematoxylin and eosin staining; bar100 μm)|
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|Figure 4: The tumor cells showing positive expression of the glial fibrillary acidic protein (bar100 μm)|
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|Figure 5: The tumor cells showing positive expression of S100 protein (bar100 μm)|
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| » Discussion|| |
Intramedullary PAs account for 2–9% of CNS PAs.,, In our study, symptomatic adult intramedullary PAs constituted 0.48% of intraspinal tumors (n = 1458) and 6.5% of CNS PAs (n = 107) during the same period. Thus, the rarity of the tumors was obvious. The tumors were mostly located in the cervical and thoracic regions.,,,,,,,, Presthesia is the most common initial symptom. Sphincter dysfunction usually occurs late in the clinical course unless the tumor is closed to the CONUS region.,, The slow clinical course (mean: 21.5 months) reflects the benign nature of PAs; nevertheless, one patient presented with acute hydrocephalus., Some authors speculated that it is caused by elevation of cerebrospinal fluid protein content, leptomeningeal infiltration by tumor cells, and obliteration of the cisterna magna due to rostral extension of the tumor., However, these hypotheses need to be further confirmed.
In our series, intramedullary PAs are a solid portion associated with variably cystic degeneration on MRI. These tumors are hypo- or isointense on T1WI, hyperintense on T2WI. After gadolinium administration, variable heterogeneous enhancement can be found. On the axial view, most tumors grow eccentrically within the spinal cord. The differential diagnosis includes grade II ependymomas and high-grade astrocytomas. The incidence rate (14.3%) of syringomyelia in our patients is much lower than that (87.5%) in patients with grade II ependymomas. And, furthermore, grade II ependymomas are usually located in the center of the spinal cord due to the origin of ependymal cells of the central canal. However, ependymomas may grow into huge masses, which causes the character of central localization unidentifiable. Moreover, high-grade astrocytomas also have the characteristic of eccentric localization and heterogeneous enhancement. Therefore, the preoperative diagnosis of adult intramedullary PAs is difficult. The accurate diagnosis mainly depends on pathology. Histologically, well-differentiated bipolar or stellate-shaped cells in a loose spongy microcystic background were present together with numerous hyalinized blood vessels. A few Rosenthal fibers were identified. GFAP and S-100 protein were the most common markers.
Currently, intramedullary PAs are mainly treated by surgical resection. The goal of surgery is to maximal safe resection of the tumor with intraoperative monitoring. In our series, four cases (57.1%) showed a well-demarcated dissection plane, and GTR can be achieved. In the other three cases (42.9%), technical problems of the ill-defined margin of the tumor prevented GTR. For these cases, STR for decompression is acceptable to avoid severe neurological deficits.
Thus far, the use of radiotherapy for PAs remains controversial. Some authors advocated radiotherapy for residual tumor after STR,, but others thought that the procedure may be ineffective., In our study, two cases of STR received radiotherapy, and one of them had mildly residual tumor regrowth. Recently, Colnat-Coulbois et al. suggested that intracavitary 186rhenium brachytherapy of intramedullary cystic PA achieves excellent stabilization of the cyst. The definitive role of radiotherapy still needs further research. In pieces of literature, some pediatric patients underwent postoperative chemotherapy with carboplatin or vincristine and lived with no tumor progression.,,, However, there is little evidence that chemotherapy is effective for adult PAs. Therefore, none of the patients received chemotherapy in our study.
Although PAs are considered benign neoplasms, cranial metastasis occurred in one case and the patient died from ascending spread astrocytoma. Thus, close clinical follow-up with neuroaxis MRI is needed. When a residual tumor regrows with clinical progression, early reoperation is recommended.,,,
Adult intramedullary PAs are extremely rare, and the accurate diagnosis depends on pathology. GTR is the best treatment and the outcome is favorable. STR increases the risk of tumor recurrence, and regular follow-up is necessary. Due to uncertain therapeutic efficacy, radiotherapy should be considered carefully for cases of STR.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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