Acta Neurochir (Wien) (2004) 146: 629–633 DOI 10.1007/s00701-004-0230-7
Case Report Cerebral astroblastoma E. Caroli1 , M. Salvati2 , V. Esposito3 , E. R. Orlando1 , and F. Giangaspero2 1
Ospedale S. Andrea, Department of Neurosurgery, University of Rome ‘‘La Sapienza’’, Rome, Italy Department of Neurosurgery, INM Neuromed IRCCS, Pozzilli (Is), Italy 3 Department of Neurological Sciences, Neurosurgery, Policlinico Umberto I University of Rome ‘‘La Sapienza’’, Rome, Italy 2
Published online April 13, 2004 # Springer-Verlag 2004
Summary Background. Astroblastoma is a rare glial tumour about which little is known. Method. We report a case of cerebral high grade astroblastoma and discuss the clinical, histopathological, surgical, radiological and prognostic features of this tumour, in the light of the pertinent literature. Result. Present patient had an initial histological diagnosis of glioblastoma multiforme. Three years later an histological revaluation was performed and revealed a high grade astroblastoma. Our patient underwent surgical removal and radiotherapy; five years after the operation he is alive and without evidence of recurrence. Interpretation. Classification and histogenesis of this tumour is still debated. The lack of a clinicopathological correlation makes the prognosis of this tumour unpredictable. The optimal management is not defined, but total resection and post-operative radiotherapy seem to be the effective means to treat the astroblastoma. Keywords: Astroblastoma; brain neoplasm; glioma; histological study.
Introduction Astroblastoma is a well-circumscribed, solid or cystic, often superficially situated tumour with a distinctive perivascular orientation of epitheliod neoplastic cells [6]. It is classified as an uncommon glial tumour by International Classification of Tumors of the Central Nervous System proposed by the World Health Organisation [15]. Astroblastoma is one of the rarest central nervous system gliomas [13]. This tumor mostly occurs during the first 3 decades of life, without a sex, race or familiar predominance. Congenital forms have been described [17]. Astroblastoma typically present as a
spherical tumour in the cerebral hemispheres, but other reported sites include the corpus callosum [10, 11], the cerebellum [19], brainstem [23], optic nerve [23] and cauda equina [11]. Astroblastoma may pose a diagnostic problem to anyone unfamiliar with its architectural and histological features [6]. The aim of this report is to describe a case of temporal astroblastoma and discuss the clinical, histopathological, radiological, surgical, prognostic and therapeutic features of this rare tumour in the light of the pertinent literature. Case report A 30-year-old man presented at our Institution in coma. A CT showed a large superficial left temporal tumour with inhomogeneous enhancement (Fig. 1A). Considerable shift of the midline structures was present, but perilesional edema was scarce. A craniotomy was performed and a tumour was found beneath the leptomeninges. The tumour was lobulated, soft, reddish, well circumscribed, and scarcely suckable. A cyst containing yellowish fluid was evident within the tumour. Surgical resection was reported as total. Immediate postoperative MRI confirmed the surgeon’s report of total resection. Histological diagnosis was glioblastoma multiforme. The patient received postoperative radiotherapy (whole-brain with 60Co) and chemotherapy with Temozolomide. Three years later a histological revaluation was performed and revealed a high grade astroblastoma (Fig. 1B–D, 2). Ample samples were taken from the operative specimen, the tissue architecture was uniform and similar. There was moderate vascular hyalinization (Fig. 1D) and some foci of necrosis. Tumour cells formed perivascular pseudorosettes (Fig. 1B, C, 2). Tumour borders were well demarcated from the surrounding parenchyma. MIB-1 labelling index was 8%. Increased cellularity, high mitotic activity, areas of necrosis, and vascular proliferation were observed. The tumour cells showed immunopositivity for GFA protein. Five years after the operation the patient is alive and without evidence of recurrence.
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Fig. 1. (A) Contrast enhancement CT showing a superficial and large left temporal tumor causing marked midline shift. (B, C) Overview of tumor, showing compact cellularity and cellular irregularity. The tumor cells are radially oriented around blood vessels forming pseudorosettes. (D) Photomicrograph of the hyalinized vascular walls of the tumor
Fig. 2. A particular of pseudorosette
Discussion Astroblastoma is a well-circumscribed, solid or cystic, often superficially situated tumour with a distinctive
perivascular orientation of epitheliod neoplastic cells [6]. Astroblastomas make up 0.45–2.8% of all gliomas [13]. This tumour was first described by Bailey and Bucy in 1930 [1] and since then only isolated cases have been reported [7, 11, 13, 14, 16, 22, 27]. Lately, Bonnin and Rubinstein have reported the general features of astroblastoma based on the revision of 23 patients seen by these authors in the last thirty years [3]. Brat et al. [4] have recently reported their experience in 20 patients with this tumour. The consideration of astroblastoma as a pure nosological entity has been proposed, [14, 29] but recent reports have confirmed its classification as a distinct form of astrocytic glioma [12, 13, 27]. In the most recent International Classification of Tumors of the Central Nervous System proposed by the World Health Organisation [15], astroblastoma is classified as a glial neoplasm of uncertain origin. The cell of origin of astroblastoma is unknown. Bailey and Bucy [1] postulated that astroblasts (embryonal unipolar cells with sucker feet attached to vessels) were the precursor of adult astroglia. Current knowledge about glial progenitor cells does not sustain this hypothesis
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by Bailey and Bucy [18]. Russel and Rubinstein in 1989 suggested that astroblastoma arises from a process of dedifferentiation involving mature astroglial cells [22]. Rubinstein and Herman observed a close ultrastructural and immunohistochemical similarity between tumor cells and the tanycyte, which is a cell of submammalian species with transitional features between the astrocyte and ependymal cell. During human embryogenesis, similar cells may appear transiently and astroblastoma could derive from abnormally persisting groups of such embryonal precursor cells [20]. Gains of chromosomes 19 and 20q are the reported cytogenetic aberrations [4, 6]. Shuangshoti et al. found a loss of heterozygosity at the D19S412 locus on the long arm of chromosome 19 in a patient with cerebral astroblastoma [24]. This result suggests that there is a tumour suppressor gene in this chromosomal region, which can be implicated in the pathogenesis of astroblastoma. Astroblastoma shows a characteristic appearance on neuroradiological images [5, 8, 22]. Typically this tumour appears as a large, well-delimited, lobulated, superficial, solid and cystic mass with inhomogeneous contrast enhancing and little vasogenic oedema. The solid component of the mass shows a bubbly appearance [5]. The cystic component gives the same signal as cerebrospinal fluid [8]. Punctate calcification may be present [5]. Sometimes astroblastoma resembles an extra-axial neoplasm on MR images given a preoperative misdiagnosis [2, 28]. The role of the proton MRI spectroscopy features have to be defined [2, 22]. The present case was studied only by contrast medium CT (Fig. 1). The lesion consisted of a superficially located mass producing midline shift and enhancing inhomogeneously. Macroscopically, astroblastoma presents as a superficially located mass with a clear cleavage plane that permits complete removal. The size and consistency are quite variable. The diagnosis of astroblastomas is often difficult because astroblastic aspects can be found in astrocytic tumours, in ependymomas, and in nonneuro-epithelial tumours. Astroblastic features must be present in all the tumour extension to make a diagnosis of astroblastoma. Histologically, our case showed diffusely the distinctive histological aspects of the astroblastoma defined by Bailey and Bucy [1]. Astroblastoma may be confused with an ependymoma. Distinguishing features are 1) the short and robust nature of the processes that constitute perivascular pseudorosettes in astroblastoma, 2) the hyalinization of vessels 3) the rarefied spaces between pseudorosettes 4) the absence of abundant fibrillary pattern [6, 21, 27]. In the older series
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[1] some tumours referred to as astroblastoma may have been anaplastic astrocytomas or glioblastomas in which there were astroblastomatous areas [14, 21]. Gemistocytic astrocytoma may have perivascular pseudorosettes, but gemistocyte is strongly fibrillated while astroblastoma is not [21]. The distinction between astroblastoma and nonglial papillary tumours such as papillary meningioma or metastases from papillary tumours is aided by immunohistochemical features, which show positive staining with glial markers such as GFPA and S-100. Ependymomas may show a similar immunohistochemical pattern, but GFPA immunoactivity in ependymoma is often more intense than in astroblastoma [7, 26]. As in ependymoma, focal EMA reactivity is not uncommon [1, 7]. Astroblastoma shows also an intense positivity with vimentin [7, 12]. Some authors [9, 12] sustain that this phenomenon can be explained on the basis of the primitive nature of the astroblastoma cells. Vimentin filaments are the first intermediate filaments to appear in the development of neuro-epithelial cells, with glial filaments appearing later [9]. However, co-expression of vimentin and GFPA is found also in other malignant glial tumours and normal astrocytes [3, 7]. This fact does not confirm the above hypothesis. In their review of 23 cases of astroblastoma, Bonnin and Rubistein [3] found two distinct histological types of astroblastomas: low-grade and high grade. The low grade type included astroblastomas with uniform perivascular arrangement of pseudorosettes, low to moderate number of mitotic figures, little cellular atypia, minimal or no vascular endothelial proliferation, and predominant sclerosis of the vascular walls [3]. High-grade astroblastomas showed cytological atypias, compact cellularity, perivascular cells with high mitotic rates, and hypertrophy of vascular endothelium [3]. Our case showed the features of a high grade type without cerebral infiltration, so that the tumour was removed en bloc. Although malignant astroblastomas may show infiltration of brain parenchyma, most of them are noninfiltrating [6]. Because of the rarity of astroblastomas, there is no consensus regarding their optimal management. A total removal, in view of the well demarcated nature, and radiotherapy seems be the advisable treatment. Our patient received radiotherapy and he is alive 5 years after surgery. In the series by Bonnin and Rubinstein [3], the only patient who received radiotherapy after biopsy was alive 12 years after diagnosis, suggesting a benefit from radiotherapy in these tumours. In the same series the only patient with high grade astroblastoma who did not receive postoperative radiation therapy had the
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shorter survival time (1.5 years). Cabello et al. described a patient who did not received postoperatory radiotherapy [7], and six months later presented with a local recurrence. She was re-operated on and received radiotherapy and after 10 months was recurrence-free. The role of chemotherapy is still unknown. Chemotherapy was administered to five patients of the Bonnin’s series with no real change in the prognosis [3]. Thiessen et al. described four patients treated by surgery, radiotherapy and chemotherapy [25], they concluded that the precise role of chemotherapy cannot be defined at this time. Kubota et al. [16] described one patient who received bleomycin without radiation, and was doing well 3.5 years postoperatively. Radiological evidence of a tumor response to chemotherapy is given only by Pizer et al. [17]. We have administered Temozolomide as a chemotherapeutic drug because the initial diagnosis was glioblastoma and five years after diagnosis the patient is alive. However, these data cannot have value because they involve only one case. The behavior of astroblastoma is unpredictable and the prognosis may be complicated by the potential of the astroblastoma to convert into a more malignant variant of glioma [3]. In our patient the short length of preoperative symptoms and signs and the histological features of high grade astroblastoma should be predictive of short survival, but the patient is still alive five years after the operation. The long survival of the present case might be explained by the complete excision of the lesion. The circumscription of the astroblastoma has been defined already as a probable factor determining the more favourable prognosis because it permits the total resection of even high-grade tumours [3]. Postoperative multimodal therapy could also have been responsible for the long survival of the patient. However, it has been found that sometimes there is a discrepancy between the histopathological feature and the evolution of the case [3]. Burger stated that ‘‘on terms of their histologic malignancy, astroblastomas reside along a continuum that has yet to be clearly linked to prognosis’’ [6]. In conclusion, total resection and post-operative radiotherapy seem to be the best way of treating an astroblastoma. References 1. Bailey P, Bucy PC (1930) Astroblastoma of the brain. Acta Psych Scan 5: 439–461 2. Baka JJ, Patel SC, Roebuck JR, Hearshen DO (1993) Predominantly extraaxial astroblastoma: imaging and proton MR spectroscopy features. Am J Neuroradiol 14: 946–950
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