|Year : 2018 | Volume
| Issue : 3 | Page : 214-221
Reappraisal of morphological and immunohistochemical spectrum of intracranial and spinal solitary fibrous tumors/hemangiopericytomas with impact on long-term follow-up
Prakriti Shukla1, Hanni V Gulwani2, Sukhpreet Kaur2, Devika Shanmugasundaram3
1 Department of Pathology, Hind Institute of Medical Sciences, Barabanki, Uttar Pradesh, India
2 Department of Pathology, Bhopal Memorial Hospital and Research Centre, Bhopal, Madhya Pradesh, India
3 Department of Research, National Institute for Research in Environmental Health, Bhopal, Madhya Pradesh, India
|Date of Web Publication||28-Jan-2019|
Dr. Hanni V Gulwani
Department of Pathology, Bhopal Memorial Hospital and Research Centre, Bhopal, Madhya Pradesh
Source of Support: None, Conflict of Interest: None
BACKGROUND: Hemangiopericytomas (HPCs) and solitary fibrous tumors (SFTs) are unique entities in the central nervous system (CNS) and even rarer in the spine with propensity to recurrence and metastasis. Both these tumors were detected to share the NAB2–STAT6 fusion gene with frequent morphologic overlap that necessitated the need for the combined term SFT/HPC in the CNS by the World Health Organization (WHO) in 2016. AIMS: This study aims to describe the clinical outcome of intracranial and spinal SFT/HPCs based on detailed histomorphologic and immunohistochemical features. MATERIALS AND METHODS: A retrospective analysis of these tumors was conducted over a period of 10 years from January 2006 to January 2017 at our institute. Based on the elaborative assessment of morphology and immunohistochemistry, these tumors were categorized into three grades as per WHO criteria. RESULTS: A total of 13 cases were encountered involving mainly extra-axial and supratentorial regions. Among intracranial HPCs, anaplastic subtypes constituted significantly higher proportion (39%) when compared with peripheral HPCs. Peculiar morphological patterns like micropapillae and pseudoangiomatous arrangement of tumor cells were observed in high-grade tumors. A panel of immunomarkers were used to confirm the diagnosis and rule out other mimickers. Gross total resection was achieved in 54% (7/13) of the cases with local recurrence observed in 31% (4/13). Grade II tumors showed recurrence in 28% cases. No case showed distant metastasis. CONCLUSION: To conclude, not just clinical parameters but morphologic features such as unusual patterns, mitosis, and proliferative index also play a pivotal role in predicting the clinical behaviour of SFT/HPC.
Keywords: Hemangiopericytomas, histomorphology, immunohistochemistry, intracranial, solitary fibrous tumor
|How to cite this article:|
Shukla P, Gulwani HV, Kaur S, Shanmugasundaram D. Reappraisal of morphological and immunohistochemical spectrum of intracranial and spinal solitary fibrous tumors/hemangiopericytomas with impact on long-term follow-up. Indian J Cancer 2018;55:214-21
|How to cite this URL:|
Shukla P, Gulwani HV, Kaur S, Shanmugasundaram D. Reappraisal of morphological and immunohistochemical spectrum of intracranial and spinal solitary fibrous tumors/hemangiopericytomas with impact on long-term follow-up. Indian J Cancer [serial online] 2018 [cited 2020 May 29];55:214-21. Available from: http://www.indianjcancer.com/text.asp?2018/55/3/214/250898
| » Introduction|| |
Hemangiopericytomas (HPCs) and solitary fibrous tumors (SFTs) are uncommon mesenchymal neoplasms that usually involve the skin and subcutaneous tissue. Although these tumors are the most common mesenchymal nonmeningothelial neoplasms in the central nervous system (CNS), their intracranial and spinal localization is exceedingly rare. HPCs arising from malignant transformation of Zimmerman pericytes are highly cellular, richly vascular, and are usually responsible for recurrence despite complete resection. In contrast, most SFTs occurring in the CNS have been reported to behave favorably. Consequently, both these entities were considered to be distinctive in the past. The World Health Organization (WHO) in 2016 combined these terms to SFT/HPCs due to frequent morphologic overlap.
On several occasions, clinical and radiological features of meningeal HPCs and SFTs closely mimic meningiomas leading to misdiagnosis. Due to paucity of knowledge on prognostic significance of histological grade, this study was undertaken to describe the clinical outcome in such tumors with emphasis on detailed histomorphologic and immunohistochemical features.
| » Materials and Methods|| |
A total of 13 intracranial and spinal HPC/SFT cases were analyzed retrospectively over a period of 10 years from January 2006 to January 2017. Case histories and clinical data on demography, per-operative notes, treatment, and follow-up were collected from the patients' medical records. Computed tomography (CT) and magnetic resonance imaging (MRI) images were used to study the tumor size, location, characteristics, enhancement, extent of resection, and recurrence. Imaging features were reviewed by an experienced neuroradiologist.
Histopathological and immunohistochemical analysis
In all the 13 cases, formalin-fixed paraffin-embedded tissue blocks were sectioned at 3 μm and stained with hematoxylin and eosin and reticulin stains. All cases of SFT/HPC were reclassified by two independent histopathologists in accordance with the current WHO system of Classification of Tumours of the Central Nervous System (2016). Histomorphological features including biphasic pattern, cellularity, presence of “staghorn” vasculature, hyalinization, interwoven collagen, and nuclear pleomorphism were studied and assigned a score ranging from 1+ to 3+. In evaluating the mitotic count (MC), most active areas were chosen and mitosis was counted per 10 high power fields (MC <5 per 10 high power fields – Grade II; MC ≥5 per 10 high power fields – Grade III). Necrosis and hemorrhage were scored as minimal (10%) or moderate to marked (>10%) after examining all the histological slides. Reticulin stain was graded in each case from 0 to 3+ (0, no staining; 1+, sparsely distributed; 2+, around clusters of cells; 3+, pericellular). Immunohistochemistry was conducted using 3-μm-thick sections on poly-l-lysine-coated slides by standard horseradish peroxidase technique. Selected panel of immunomarkers including CD34, Vimentin, Bcl2, CD99, EMA, and STAT6 were performed in each case [Table 1]. STAT6 immunostain was performed at a referral laboratory; all others were performed in-house. The intensity of immunoreactivity was scored as 0, absent; 1+, weak focal; 2+, weak; 3+, strong focal (<50%); 4+, strong diffuse (≥90%). Ki67 proliferative index was calculated by the manual counting method wherein an initial slide scan was performed to identify the tumor “hot spots” and the 10× objective was then used to count the Ki67-positive cells per 2000 tumor cells in real time (Ki67 <10% – low; Ki67 ≥10% – high).
Demographic and clinical profile data were entered in Microsoft Excel and analyzed using statistical software SPSS version 16 for Windows (SPSS Inc., Chicago, IL, USA). Frequency distribution was presented for categorical variables and mean and standard deviation for continuous variables. Recurrence-free survival was calculated using Kaplan–Meier method, and the differences between subcategories (age, sex, size, location, resection, grade, adjuvant radiotherapy, necrosis, mitosis, and Ki67) were analyzed using log-rank test. Univariate Cox proportional hazard model was used to predict the probability of event (recurrence) in the presence of risk factors. We used penalized maximum likelihood Cox's regression model for estimating hazard ratio to avoid convergence problem. Kappa statistics was used to find the agreement between categorization of mitosis and Ki67.
| » Results|| |
Incidence and clinical profile
During the study period, 13 cases of intracranial and spinal SFTs/HPCs were diagnosed. The incidence was 1.3% of all the primary CNS tumors, and the ratio of HPCs to meningiomas was 1:30. Of 13 cases, 12 (92.3%) cases were HPCs and 1 (7.7%) case was of SFT. The mean age at the time of diagnosis was 31 years with most cases presenting in the fifth decade. Male-to-female ratio was 1.2:1. Demographic patient data are summarized in [Table 2]. The most common presenting complaint was headache (n = 10, 77%) followed by weakness in lower limbs (n = 6, 46%), vomiting (n = 5, 38%), diplopia (n = 2, 15%), seizures (n = 2, 15%), cranial nerve palsy (n = 2, 15%), urinary incontinence (n = 2, 15%), ptosis (n = 1, 8%), and vertigo (n = 1, 8%).
|Table 2: Clinical summary of 13 cases of intracranial and spinal solitary fibrous tumor/hemangiopericytoma|
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Of the 13 cases, 10 were supratentorial, 2 infratentorial, and 1 was located in the spine. Eight (62%) were extra-axial and four (30%) were intra-axial. Spinal HPC was seen as an intradural extramedullary tumor at D8 region. Preoperative CT demonstrated tumor size ranging from 2 to 14 cm (mean: 6.6 cm). In four of the cases, tumor size was more than 6 cm. Nine cases revealed homogeneous hyperdense lesions, whereas the remaining four tumors were heterogeneously hyperdense [Figure 1]a and [Figure 1]b. Seven cases revealed mass effect with midline shift, and in two cases both solid and cystic areas were noted. Hydrocephalus was present in one case. MRI was available in eight cases only where isointense to hypointense tumors were seen on T1-weighted images and isointense to hyperintense on T2-weighted images. Five cases with homogeneous and three cases with heterogeneous contrast enhancement were recorded. Six cases revealed well-circumscribed, multilobulated, dura-based neoplasm with perilesional edema.
|Figure 1: (a) CT image of suprasellar solitary fibrous tumor. (b) CT image of large bifrontal intracranial HPC with solid and cystic areas|
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The initial treatment was in the form of surgical resection with no immediate mortality. Gross total resection (GTR) was accomplished in seven cases (54%) and subtotal resection (STR) in six cases (46%). Gamma knife radiosurgery was done in two patients after STR at 1 month and 3 months, respectively. Adjuvant radiotherapy was given in five patients [Table 2].
Histopathology and immunohistochemistry
Intraoperatively, most tumors were reddish brown, soft to firm, nonpulsatile, and highly vascular with a well-defined plane of cleavage.
This study used the revised WHO system of classification (2016) to grade these tumors where one case (8%) was categorized as Grade I, seven (54%) cases were classified as Grade II, and five (39%) cases were graded as anaplastic (Grade III) [Figure 2]a, [Figure 2]b, [Figure 2]c. Histomorphologic features have been discussed in detail in [Table 3].
|Figure 2: (a) Grade I solitary fibrous tumor. (b) Grade II classical low-grade hemangiopericytoma with many staghorn vessels. (c) Grade III anaplastic hemangiopericytoma showing markedly increased vascularity with oval to spindled tumor cells and area of necrosis (hematoxylin and eosin stain)|
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|Table 3: Histomorphological features of solitary fibrous tumor/hemangiopericytoma|
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There was only one case of Grade I tumor (SFT) seen in a 26-year-old male who presented with constant headache and loss of vision in the right eye with diminution of vision in the left eye. CT revealed an extra-axial, hyperdense mass of 6 × 5 cm located at the suprasellar region leading to optic atrophy. Histologically, it showed a moderately cellular, biphasic tumor with uniform spindle to oval cells disposed in fascicles between prominent, eosinophilic bands of collagen. Classical “staghorn” vasculature was present in some areas with few hyalinized vessels. Necrosis and hemorrhage were not evident. Mild nuclear pleomorphism was seen, and mitosis was <2 per 10 high power fields. Reticulin fibers were sparsely distributed (1+) throughout the tumor.
Histological sections from Grade II SFT/HPC cases revealed variable cellularity (range 2+ to 3+) with tightly packed monomorphic looking ovoid cells with indistinct cytoplasmic borders arranged around an elaborate vasculature. Typically, several arborizing vessels with “staghorn” configuration were seen in all cases. In all seven cases, interwoven collagen was minimal (1+ to 2+) except in two cases where focal area revealed thick intervening keloid-like collagen. Mild to moderate nuclear pleomorphism was noted, and hyalinized areas were few (1+ to 2+). Focal necrosis was seen in two cases. Large areas of hemorrhage were observed in four cases. Mitosis was low in all cases (<2 per 10 high power fields). Reticulin fibers were stained variably with a score ranging from 1+ to 3+ and dense pericellular staining (3+) observed in three cases. Of the seven Grade II HPCs, one case showed marked stromal metaplasia in the form of adipocytic differentiation and was diagnosed as lipomatous variant of HPC [Figure 3]a. Immunohistochemistry in these cases revealed strong STAT6 nuclear positivity in 12 cases and 1 of the cases showed focal but intense expression. Immunohistochemical expression of CD34 was variable and ranged from 1+ to 4+, Vimentin ranged from 1+ to 4+, Bcl2 from 0 to 2+, and CD99 from 0 to 3+. EMA was negative in all seven cases. Ki67 proliferative index was low in six cases (≤10%) but high in one case (>10%) and this case recurred after 16 months of surgery. In two cases, adjacent brain parenchyma with reactive astrocytes was included in the biopsy.
|Figure 3: (a) Low-grade hemangiopericytoma showing stromal adipocytic metaplasia. High-grade hemangiopericytoma showing focal abortive micropapillae (b) and pseudoangiomatous pattern (c) in other case (hematoxylin and eosin stain)|
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In this study, three cases (two Grade II tumors and one Grade III tumor) with overlapping features of HPC and SFT were observed with areas showing compactly arranged ovoid cells and many dispersed staghorn-like vessels, on one hand, and thick collagenous bands intermixed with spindle-shaped cells, on the other hand [Figure 4]a, [Figure 4]b, [Figure 4]c. In all these cases, 60%–70% of the areas showed typical HPC-like pattern, whereas 30%–40% of the areas were of SFT type. Mitosis was <2 per 10 high power fields in two cases and 6–7 per 10 high power fields in one case. Reticulin fibers were seen around individual cells (3+) in classical HPC areas, whereas its expression was 0 to 1+ in areas with dense collagen. Immunohistochemical expression with CD34 was 3+ in two cases and absent in the other case. CD99 was 3+ in one case and 1+ in two other cases. Bcl2 showed 2+, 1+, and 0 expression in these three cases. In these cases, Ki67 index was high in two cases (8% and 25%, respectively) and low in one case (<2%). In Grade III SFT/HPC group, all five tumors exhibited highly cellular areas with round to ovoid cells arranged in sheets displaying moderate nuclear pleomorphism with little to moderate interwoven collagen. In two cases, unusual patterns were noted as in one case focal area showed attempt to micropapillae formation and in one another case pseudoangiomatous arrangement of the tumor cells was seen [Figure 3]b and [Figure 3]c. Staghorn vasculature and areas of hyalinization ranged from +1 to+3. Necrosis was minimal in four cases, but one case showed large areas of necrosis with only a focal area showing viable tumor cells. Hemorrhage was evident in all cases. Hypercellular areas demonstrated numerous atypical mitotic figures ranging from 6 to 20 mitosis per 10 high power fields. In three of the cases, MC was ≥10 per 10 high power field. Reticulin fibers showed pericellular staining in the classical HPC areas and the staining was minimal to absent in the anaplastic areas. CD34 was not expressed in three cases, but 3+ and 4+ positivity was noted in two other cases. Vimentin was 0 to 2+ positive, Bcl-2 was 2+ in two cases, and absent in other cases. CD99 was 3+ in one case, 1+ in another case, and absent in three other cases. EMA was negative in all cases. Ki67 proliferative index was ≥10% in all five cases. Immunohistochemical expression of the various antibodies in representative cases of grade II and III hemangiopericytoma was as depicted in images [Figure 5]a, [Figure 5]b, [Figure 5]c, [Figure 5]d, [Figure 5]e.
|Figure 4: Tumor showing overlapping features of SFT/HPC. (a) Staghorn vessels with little interwoven collagen. (b) Dense keloid-like collagen (hematoxylin and eosin stain). (c) Junctional area showing thick reticulin fibers in classical HPC areas and sparse fibers in SFT-like areas (reticulin stain)|
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|Figure 5: Representative anaplastic hemangiopericytoma. (a) Ki67 index 15%–20%, (b) CD34 positive in tumor cells. Grade II hemangiopericytoma exhibiting strong nuclear expression of Bcl2 (c), strong vimentin expression (d), and strong nuclear expression of STAT6|
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In this study, the morphology of recurrent tumors was similar to their primary tumors except in one case that exhibited increased cellularity. The score for nuclear pleomorphism changed from 1+ to 2+ in two cases. Expression of reticulin reduced from 3+ to 1+ in one case. Immunohistochemistry showed decreased CD34 expression in two cases from 1+ to 0 and 3+ to 1+ respectively; expression of vimentin increased in one case (2+ to 4+); reduced reactivity was seen with CD99 and Bcl2 in one case each. Ki67 proliferative index increased in two recurrent tumors from 9%, 11% in primary tumors to 11%, and 21% in recurrent ones, respectively.
Follow-up and recurrence
The follow-up period in these patients ranged from 7 to 106 months. One patient expired 7 months after the first operation. Local recurrence occurred in four cases (30.7%) at an interval of 16, 18, 24, and 32 months from initial surgery. Out of these four cases, two tumors were Grade II and the other two were Grade III. In these patients, a second surgery was performed in three cases while two of these patients also received adjuvant radiotherapy. One patient received only chemotherapy after recurrence and was doing well at 14 months of follow-up. None of the cases presented with distant metastases in this study. Due to the limited sample size in this study, multivariate analysis could not be done and statistically significant results were not obtained. Hazard ratio using penalized Cox proportional hazards regression for comparison of various independent clinical and histologic variables with reference to mean time period for local recurrence is described in [Table 4]. Graphical illustration of univariate parameters is depicted to compare the significance of large tumor size > 6 cm, higher histologic grade, adjuvant radiotherapy, and Ki67 index in predicting recurrence-free survival in intracranial HPCs [Figure 6], [Figure 7], [Figure 8], [Figure 9].
|Table 4: Univariate assessment of hazard ratios using penalized Cox proportional hazards regression|
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|Figure 6: Correlation analysis between large tumor size and recurrence-free survival|
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|Figure 7: Correlation analysis between histologic grade and recurrence-free survival|
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|Figure 8: Correlation analysis between adjuvant radiotherapy and recurrence-free survival|
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|Figure 9: Correlation analysis between Ki67 index and recurrence-free survival|
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| » Discussion|| |
Stout and Murray (1942) first described the term HPC, but Begg and Garret (1954) reported the first case of intracranial HPC in the left parietal region., The first report of CNS SFT was described by Caroli E et al. in 1996. Although both SFTs and HPCs share inversions at 12q13, fusing the NAB2 and STAT6 genes, it is difficult to predict the clinical behavior of these neoplasms, as historically HPCs were described to have worse prognosis than SFTs. They account for less than 1% of all primary CNS tumors. Incidence of HPC/SFT group of tumors at our institute was 1.3% which was similar to the incidence reported by Park et al. and Alen et al., Intracranial HPC/SFT to meningioma ratio was 1:30. In three large series of dural neoplasms, the ratio of meningeal HPCs to meningiomas was approximately 1:40, 1:50, and 1:60, respectively.,,
In our study, three recurrent cases had tumor size more than 6 cm. Rutkowski et al. stated that tumors more than 6 cm recurred early in their study. The mean age at the time of diagnosis was 31 years which was comparatively lower as reported by Rutkowski et al. and Ramakrishna et al. with a mean age of 48 and 51 years, respectively., The youngest patient was a 13-year-old boy with a lesion in the spine at D8 region. The study by Muraszko et al., with four cases of spinal HPC, revealed a 11-year-old female as the youngest patient with tumor at T11 level that recurred after 3 years despite surgical resection and radiotherapy. Seven (54%) of the patients were men with a male-to-female ratio of 1.2:1. Similar data were reported by other studies from various parts of the world including Korea, London, and Washington.,, The most common complaint was headache followed by vomiting and weakness in lower limbs and the commonest site was supratentorial with the majority of the tumors occupying the temporoparietal region as was seen in a study by Noh et al.
Distinguishing SFT/HPC from other skull-based tumors such as meningiomas, schwannomas, and sometimes neurofibromas is essential for proper management. In our study, preoperative CT revealed hyperdense masses of mostly large sizes (≥6 cm) producing mass effect, midline shift, perilesional edema, but no calcification. These findings were in corroboration with the CT findings of Servo et al. On MRI, most lesions were isointense to hypointense on T1-weighted images and isointense to hyperintense on T2-weighted images with homogeneous contrast enhancement. The majority of them showed well-circumscribed, multilobulated, dura-based neoplasm with perilesional edema. Guthrie et al. and Cosentino et al. described similar findings of these tumors on MR., However, CT and MR features are often deceptive leading to misinterpretation of the diagnosis as was observed in our study with nine cases misdiagnosed as meningioma. Unlike meningiomas, hyperostosis of adjacent bone and intratumoral calcifications are often absent in HPCs. Therefore, in dura-based hypervascular masses, a possibility of HPCs/SFTs must be considered as these tumors are highly aggressive and tend to recur and metastasize frequently.
Histologically, low-grade tumors (Grade I) show variable cellularity, interwoven collagen, and low MC against high-grade or anaplastic tumors that demonstrate hypercellular areas with moderately pleomorphic cells and mitosis of more than 5 per 10 high power fields often in conjunction with necrosis and/or hemorrhage. In our study, anaplastic HPCs (Grade III) constituted 39% of all HPC/SFT tumors in comparison to 54% of Grade III tumors observed by Zhou et al. in 2012. Unusual patterns like micropapillae and pseudoangiomatous arrangement of tumor cells were observed in Grade III tumors. In a study by Ishizawa et al., anaplastic tumor revealed prominent papillary structures where atypical cells were seen arranged along the fibrovascular core.
While Grade II tumors reveal delicate, striking, pericellular reticulin fibers, Grade I tumors generally show sparsely distributed fibers or sometimes around lobules of tumor cells. Expression of reticulin stain may differ in anaplastic tumors as in our study densely populated areas revealed no staining, whereas HPC-like areas showed pericellular staining and SFT-rich areas had few collagenous fibers. Tihan et al. also made similar conclusions while comparing 18 cases of SFTs with meningeal HPCs.
Until now, CD34 was considered to be the most specific marker for HPC/SFT group of tumors, but since its expression in hematopoietic stem cells, endothelial progenitor cells, myeloid progenitor, cells and certain mesenchymal cells has been documented, it can be found in tumors arising from all these cells. Nevertheless, CD34, CD99, Bcl2, and VIM almost always display strong immunoreactivity in Grade I tumors previously contemplated as SFTs. While CD34 positivity has been reported in 95%–100% of the cases, its deficiency does not rule out these tumors. STAT6 was the only consistent marker that was positive in all cases and was also extremely helpful in distinguishing from histologic mimics. Bcl-2 is expressed in 80%–100% of the cases and CD99 is also strongly exhibited with a positive expression rate of 75%–100%.,, In our study, there was one case of Grade I tumor that showed similar results, whereas Grade II and III tumors showed weak positivity for CD34, variable expression with CD99 and Bcl-2. Han et al. described that previously CD34, CD99, and Bcl2 were considered positive immunomarkers for diagnosing HPC/SFT, but now their expressions vary significantly and can even be seen in other tumors that mimic HPCs. These tumors are typically epithelial membrane antigen, cytokeratin, smooth muscle actin, and S-100 negative as was reported in our study also.,
In our study, mean Ki67 proliferative indexes in Grade I, Grade II and anaplastic Grade III HPCs were 1%, 11.14%, and 17.4%, respectively. In recurrent tumors, the mean Ki67 was 12.5%. However, the sample size was too small for statistical significance.
Nearly 10%–15% of these tumors display malignant potential by recurring at their primary site or emerging again in the form of distant metastasis., In this study, 28% of Grade II tumors showed recurrence. Zweckberger et al. made similar remarks about Grade II tumors.
Complete surgical resection of the tumor is the key to successful management. In our study, complete resection was achieved in 54% of the tumors and 57% of these did not show any recurrence and were doing well at mean follow-up of 20 months. Thus, GTR in the first surgery offered better survival rate. However, two of the patients, one each of Grade II and Grade III with intraoperative GTR of tumor, also showed recurrence. In a study by Zweckberger et al., complete resection was achieved in 60% of the cases and local recurrence was observed in 20% of the cases. Local recurrence occurred in 30.7% of the patients in whom radiation was not given. Recurrence in our series was attributed to the large size of the tumor where complete resection was not done, lack of postoperative radiotherapy, or due to anaplasia (Grade III) where MC was raised and/or Ki67 proliferative index was high. When radiation was given in recurrent cases along with second surgery, survival of these patients improved. Thus, it is highly recommended to combine adjuvant therapies with surgical resections for better clinical outcome.
| » Conclusion|| |
Diagnostic insight by neuropathologist is of paramount importance in recognizing these tumors as they are misdiagnosed as meningiomas on radiology. Histological grading of these tumors based on WHO 2016 classification is important for patient's prognostication and management. It is not unusual to encounter these mesenchymal tumors exhibiting overlapping histomorphologic features of SFT and HPCs. Among intracranial HPCs, anaplastic subtypes constitute a significantly higher proportion when compared with peripheral HPC. Keeping in view the diverse histomorphologic spectrum, a panel of immunohistochemical markers is necessary to support the diagnosis of HPC in nonclassical cases. Multiparametric approach is essential for deciding postsurgical patient's management. The parameters of prognostic significance are not only clinical such as large size, location, and extent of resection but also several morphologic parameters such as histologic grade, high cellularity, abnormal patterns, nuclear pleomorphism, mitoses, necrosis, and Ki67 proliferative index also play a pivotal role in predicting recurrence.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9]
[Table 1], [Table 2], [Table 3], [Table 4]