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An Institutional Review of 10 Cases of Spinal Hemangiopericytoma/Solitary Fibrous Tumor
Correspondence Address: Source of Support: None, Conflict of Interest: None DOI: 10.4103/0028-3886.284374
Keywords: Extramedullary, hemangiopericytoma, intramedullary, solitary fibrous tumor, spinal cord neoplasm, spinal neoplasmKey Message: Spinal haemangiopericytomas are extremely rare. Gross total excision should be the aim. Anaplastic tumors and residual tumors should receive post-operative adjuvant therapy. Prognosis is good with gross total excision and delayed recurrence can occur.
First described by Stout and Murray in 1942, hemangiopericytoma is a rare tumor of the central nervous system. It was thought to arise from pericytes surrounding the blood vessels.[1] In the 2007 “WHO classification of CNS tumors,” they were classified as tumors of meninges of mesenchymal origin.[2] In the 2016 “WHO classification of CNS tumors,” it was restructured along with solitary fibrous tumors as a separate entity ranging from grade 1 to grade 3.[3] They account for 1% of all CNS tumors. The brain is the commonest location for these tumors and spinal occurrence is a rare event.[4] Zhang et al. have recently published an extensive review of spinal hemangiopericytoma. However, most of the studies reviews are comprised of case reports and only a few[5] case series exist to date in the literature.[5],[6] In the largest case series published to date, Liu et al. classified spinal hemangiopericytomas into three types and five subtypes—type I is extradural tumor (IA- intracanal, IB- extracanal), type II is intradural type (IIA- extramedullary, IIB- intramedullary), and type III is intra to extradural and paravertebral type.[7] In our center, we have reviewed 10 cases of spinal hemangiopericytoma in the last 11 years which includes both adults as well as pediatric patients for their clinical presentation, radiological features, management, pathology, and outcomes.
A total of 10 patients with spinal hemangiopericytomas were treated at our institute over the last 13 years. The medical records of all patients were reviewed retrospectively for clinical features, surgery performed, histopathology, and postoperative adjuvant therapy and follow up. Histological analysis was reviewed to confirm the diagnosis of hemangiopericytoma. The extent of resection was reviewed from the operative notes and postoperative follow up MRI at three months was available in all patients. The patients were recently reviewed on outpatient basis by two independent neurosurgeons and their follow-up imaging were reviewed. The collected data were then analyzed.
From 2004 to 2017, 10 patients, five male and five female, with spinal hemangiopericytoma underwent treatment in our institute. The mean age at diagnosis was 34.7 years (SD 11.43 years) (Range 12-52 years). Clinical characteristics from the patients are summarized in [Table 1].
The duration of clinical symptoms ranged from 3 days to 1 year (Median 3.5 months) at the time of diagnosis. Patients most commonly were seen at the time of spastic paresis and sensory loss, with pain being a rather uncommon symptom. Spastic paresis was progressive in most patients with one pediatric patient having sudden-onset paresis. Bladder or bowel involvement was commonly seen (70%). Two patients presented with recurrent tumors after been operated at other centers. One of them had been operated twice outside. Contrast-enhanced MRI scans were done preoperatively in all the cases. The MRI findings varied widely and were nonspecific. Extradural, intradural- extramedullary, and intramedullary tumors were found, with intradural extramedullary (Type IIA) being the most common. Location and morphology of the tumor are summarized in [Table 1]. Nine patients underwent surgery as the primary treatment while one patient was not operated in view of metastatic disease. None of our patients underwent preoperative embolization. A posterior approach was taken for all nine cases. One patient with type 3 hemanigopericytoma underwent fixation along with tumor decompression. Of the eight patients operated by us, seven patients (77.7%) underwent gross total excision and two (22.2%) had subtotal excision. The reasons for subtotal excision included an intramedullary tumor (type IIB) with poor plane between tumor and healthy cord in one patient and a recurrent tumor (type IA) with dense adhesions in the second patient. Histopathological evaluation shows hemangiopericytoma in all the cases. Anaplastic variety (Grade 3) was seen in two out of nine patients (22.2%). Mitosis was a common occurrence in all specimens with rate of mitoses varying from rare to 13 per 10 HPF. Seven slides could be reviewed for STAT 6 positivity [Figure 1], [Figure 2] and [Table 2]
One patient developed postoperative CSF leak and wound infection and managed conservatively with antibiotics. The postoperative course was uneventful in the rest of the patients. Postoperative contrast-enhanced MRI was done in all the patients after 3–6 months. Six patients (60%), including two patients with subtotal excision, underwent postoperative adjuvant external beam radiotherapy. Five patients received ifosfamide and epirubicin in addition to radiotherapy. These patients were followed up at 6 months after radiotherapy and annually thereafter. Mean follow-up was 68 months (SD 42.07) (range 3–162 months). During the follow-up period, two patients expired. One patient (case 2) with type IIB lesion who underwent a subtotal excision was admitted at two years postop with hyponatremia and seizures. He underwent ventriculoperitoneal shunt after emergency noncontrast computed tomography of the head showed evidence of communicating hydrocephalus. He later succumbed to refractory hyponatremia. The second patient (case 4) had been operated twice at another center and presented with recurrence. He had not received adjuvant therapy following the previous surgeries. He underwent subtotal excision followed by post op radiotherapy and chemotherapy. He developed extensive metastasis including brain metastasis after five years and expired. At last follow up, seven patients were healthy and had improved significantly. All were ambulatory and resumed their routine activities. Contrast MRI done at last follow-up did not reveal any tumor in those patients. One patient (patient 8) was not operated for spinal lesion. She expired after 3.5 years of surgery for cranial lesion due to a stomach malignancy. Survival analysis Among the nine patients operated for spinal hemangiopericytoma, the 1-, 3-, and 5-year survival rates were noted to be 100%, 88.9%, and 77.8%, respectively. Mortality was observed in both patients undergoing subtotal resection. The recurrence-free survival at 3 and 5 years were 88.9% and 77.8%, respectively. Two patients developed recurrence at more than five years of follow up. One of them had a grade 1 lesion who developed a recurrence at six years and underwent redo surgery with gross total excision. He has been recurrence free for the last seven years. The second patient had a grade 3 lesion and was operated 3 times. He expired after 5 years of the last surgery due to extensive metastasis. Illustrative case 5 A 12-year-old female child, presented with acute conus cauda syndrome for the past 3 days. On evaluation, she was found to have an intradural extramedullary lesion with contrast enhancement at D11- L1 level. She underwent D11 to L1 laminectomy with gross total excision of the tumor. Intraoperatively, the tumor was seen to be an IDEM with no cord invasion. Histopathological features were suggestive of anaplastic hemangiopericytoma grade III with MIB-1 labeling index of 35% and Vimentin, EMA, and Bcl-2 positivity. She received postop radiotherapy and adjuvant chemotherapy including ifosfamide and epirubicin. At the last follow-up, the patient had significant neurological improvement with normalization of lower limb power and was preparing for college examinations. Follow-up MRI did not show any residual disease [Figure 3].
Hemagiopericytomas are rare entities of the central nervous system with uncommon occurrence in the spine. Prior to this case series, only two other large cases series have been published.[6],[7] They are most commonly seen in the cervicodorsal region.[5] In 2007 WHO classification, they were considered a part of mesenchymal and meningothelial origin and graded as 2 and 3.[8] However, the 2016 CNS WHO has classified them as separate entities along with solitary fibrous tumors and assigned three grades within the entity of solitary fibrous tumor/hemangiopericytoma. This was supported by the discovery of a specific fusion protein and nuclear presence of STAT6 that characterized all solitary fibrous tumor and hemangiopericytoma.[9] Grade I refers to the highly collagenous, relatively low cellularity, spindle cell lesions previously diagnosed as solitary fibrous tumor; grade II includes more cellular, less collagenous tumors with plump cells and “staghorn” vasculature; and grade III most often corresponds to what was termed anaplastic hemangiopericytoma, diagnosed on the basis of 5 or more mitoses per 10 high-power fields. Hemangiopericytomas can express a wide variety of markers such as Bcl-2, Vimentin, and factor XIIIa and often show CD 34 positivity.[10],[11] In addition, they are negative for EMA and S-100, that help differentiate them from fibrous meningioma and schwannoma, respectively.[12] In the present series, CD34 and MiC-2 were found in 77.8% and Bcl-2 in 80% patients and all the tumor specimens were uniformly negative for epithelial tissue markers like EMA. Hemangiopericytomas show slight male predilection. They are aggressive tumors with the potential for wide-spread metastasis.[7] Hemangiopericytomas of the spine commonly present with pain, motor weakness, and sensory symptoms.[5] However, the pain was an uncommon symptom in our series. A majority of our patients had sphincter involvement, unlike other studies that suggested that sphincter involvement is relatively rare and late.[7],[13],[14] Diagnostic imaging and embolization In early literature, radiologic features of hemangiopericytoma may be found in the earlier reports of “angioblastic meningioma,” a term that was often used before SFT and HPC were recognized as distinct entities.[15] The radiological findings in spinal cases were difficult to differentiate from other spinal tumors and a preoperative diagnosis of hemagiopericytoma is rarely made.[16] On the basis of imaging, Liu et al. classified them into three categories and five subcategories. Type II A (intradural extramedullary) is the commonest variety.[7],[17] Intramedullary (type IIB) and pure extradural (type I) tumors are rare.[17],[18],[19] MRI imaging can be nonspecific and lesions can be isointense to hyperintense on T1 and T2W imaging, the presence of vascular flow voids with heterogenous contrast enhancement.[16],[20] Although such features can be shared by meningiomas, the absence of calcification, hyperostosis, and the relative narrow base and nodularity of hemangiopericytoma can help to differentiate them. Angiography is rarely required for diagnosis and is used for preoperative embolization of large tumors.[21] A single-stage percutaneous embolization and resection has also been described [Table 3].[22]
Treatment and adjuvant therapy Surgery is the primary mode of treatment for spinal hemangiopericytoma.[7] Most neurosurgeons aim for gross total resection in such patients.[4],[23],[24],[25] However, Liu et al. did not find any difference in the survival or recurrence rates depending upon the extent of resection. Therefore, they advised caution in high-risk patients such as those with type IB and III tumors.[7] In our study, two patients undergoing subtotal resection died. One of them was secondary to hyponatremia and recurrent seizures. The second patient died of extensive metastatic disease after having been operated thrice. However, two of our patients did develop recurrence after gross total resection which could be treated by reoperation. We agree with Liu et al. that extent of resection needs to be weighed against potential neurological deficit. Despite high local control rates, hemangiopericytomas of the CNS remain difficult to cure with surgery alone. Therefore, postoperative RT has been implemented in the past and has established a clear indication for postoperative RT.[26] Radiotherapy has been found to improve local control and overall survival.[23],[27],[28],[29] Few studies have shown no benefit from radiotherapy.[30] As a result of the uncommon occurrence of spinal hemagiopericytoma, no strong evidence is available on the role of radiotherapy. In studies by Liu et al. and Jia et al., there was no effect of radiotherapy on survival or recurrence.[7],[31] Most of our patients (60%) also underwent radiotherapy. With the rarity of these lesions, we doubt that evidence based guidelines for the same will be easily available in the near future. Similarly, adjuvant chemotherapy has also been used with limited success for intracranial lesions.[32],[33] Doxorubicin, cyclophosphamide, ifosfamide, vincristine, and dacarbazine have been used.[34],[35] Five of our patients received chemotherapy consisting of ifosfamide and epirubicin and tolerated them well. Stereotactic radiosurgery has been used for intracranial hemangiopericytomas with reasonable tumor control rates.[36],[37],[38],[39] Only a few spinal hemangiopericytomas have been included in such studies. Liu et al. used SRS in two of their cases with satisfactory tumor control.[7] None of our patients received radiosurgery. Because of its rarity, effective treatment plan and further surveillance program are yet to be decided. Studies have shown a 5-year survival rate and a local tumor control rate of 76%.[7] Zhao et al. had a higher recurrence rate (73%) with extradural than intradural (50%) tumors. The survival rates associated with spinal tumors seem to be lesser than their cranial counterparts with 5-year rates ranging from 85 to 95%.[10],[23] The current recommendation for spinal hemangiopericytoma is gross total resection of tumor, when possible.[5],[7],[31] Postoperative radiotherapy is commonly used especially in the setting of anaplastic tumors. However, its survival benefit is yet to be proved. As can be seen from our study, recurrence can occur even after gross total excision and even in a delayed manner.
Spinal hemangiopericytomas are rare tumors and with nonspecific imaging features. The aim of the surgery should be maximal resection while preserving neurological status. Recurrences are known to occur even after prolonged follow up. Postoperative chemotherapy and radiotherapy may help in local tumor control. The role of stereotactic radiosurgery remains to be defined. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.
[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2], [Table 3]
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