Clinical, histological and imaging aspects of pleomorphic xanthoastrocytomas: the key is in the name

Aspectos clínicos, histológicos e imagenológicos dos xantoastrocitomas pleomórficos: a chave está no nome

EDITORIAL

Clinical, histological and imaging aspects of pleomorphic xanthoastrocytomas: the key is in the name

Aspectos clínicos, histológicos e imagenológicos dos xantoastrocitomas pleomórficos: a chave está no nome

Leandro Tavares Lucato

MD, PhD; Neuroradiologist. Instituto de Radiologia do Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo (USP); Centro de Diagnósticos Brasil (CDB), São Paulo SP, Brazil

^{Correspondence}

Pleomorphic xanthoastrocytoma (PXA) is a rare tumor of the central nervous system, first described in 1979¹. It was added to the World Health Organization (WHO) classification of tumors in 1993². First reports emphasized that despite their highly pleomorphic and bizarre cytology, which suggested a malignant behavior, these tumors appeared to have a relatively favorable prognosis in most of the cases¹, with a 75% overall survival at 5 years³.

PXA were probably some of the first tumors in whose characterization immunohistochemical markers were essential. Namely, the demonstration of glial fibrillary acidic protein (GFAP) led to the definition of PXA as a new clinicohistopathologic tumor entity of astrocytic nature¹. Prior to its initial description, PXA was often classified among giant cell glioblastomas or mesenchymal tumors such as fibrous xanthomas or sarcomas (due to its rich reticulin network)⁴.

In the following years, clinical and surgical series were reported⁵; patients with PXA typically present as children or young adults with almost 70% under 30 years of age, and equal frequency of occurrence in both males and females^4,6. Presenting symptoms consist primarily of seizures, often of long duration^3,4; followed by dizziness, headache and focal neurological deficit⁶.

Studies focusing on imaging aspects of PXA demonstrated that these tumors are often superficial with leptomeningeal extension and involve the temporal lobe most frequently (up to almost 50% in a large series)⁴; other common locations include the parietal, frontal, and occipital lobes. Patterns of presentation can be purely cystic (uni or multilocular), mixed cystic-solid and purely solid; the solid portions usually enhance intensely after the use of contrast material^6,7. Remodeling of the adjacent calvarium can be appreciated, related to the slow growth of this superficial lesion.

Surgery is clearly the treatment of choice, and the extent of primary resection has great impact on prevention of recurrence and survival rates. Cases in which a gross total removal is achieved, a "wait and see" approach can be recommended followed, if necessary, by additional surgery for residual and/or recurrent tumor⁴. At present, the role of adjuvant radiotherapy and/or chemotherapy remains uncertain, but it seems that patterns of care are following the treatment patterns of gliomas³.

More recently, unusual aspects pertaining PXA started to be reported, such as atypical locations (especially in the posterior fossa and spine^4,8) and an association with neurofibromatosis type I⁹.

Uncommon histological aspects include descriptions of PXA in conjunction with ganglioglioma, dysembryoplastic neuroepithelial tumor, oligodendroglioma and even cortical dysplasia^10,11. This finding led some authors to speculate about the histogenesis of PXA as deriving from bipotential precursor cells, in opposition to previous analyses that proposed mesenchymal precursors or a subclass of astrocytes as the tumor origin¹².

Prognosis seems to be worse than initial reports in a subset of patients. Although PXA is considered a WHO grade II tumor, anaplastic transformation can occur in up to 15 to 20% of patients⁴. Histological signs of anaplasia can be observed in this regard, as manifested by increased mitotic activity, acquisition of necrosis and/or endothelial proliferation; however, sometimes recurrence is associated with tumors that remain histologically unchanged⁴. Leptomeningeal dissemination is usually related to malignant features of PXAs, although this is not always the case¹³.

Gonçalves et al.¹⁴, in the present issue of Arquivos de Neuro-Psiquiatria, shed light on some interesting topics related to histology and imaging aspects of PXA, in agreement with the literature and also adding local flavor to the study of these tumors.

First of all, in their sample they corroborate what literature states about the bad prognosis of PXA when detected in elderly patients, as their oldest patient deceased only one month after surgery. In this age range PXA usually show a more severe clinical picture, and more ominous histological features¹⁵.

Another interesting topic was the association found between peritumoral edema and a short time interval (less than one year) between the beginning of the clinical picture and the diagnosis. This finding contrasts with most of the published data, as PXAs are commonly associated with long-standing symptoms. Although further studies are essential, as the authors underscore, this association deserves distinction.

It is also extraordinary that in four out of the nine presented cases there was an association between PXA and other tumors/cortical dysplasia; reinforcing what was already mentioned above and demonstrating the need of a detailed histological analysis.

Finally, when dealing with clinical, histological and imaging aspects of PXA, if there is a central characteristic common to all of them, it is pleomorphism, and therefore, one can really conclude: the key is in the name.

Conflict of interest

There is no conflict of interest to declare.

Received 20 November 2012

Accepted 27 November 2012

• 1. Kepes JJ, Rubinstein LJ, Eng LF. Pleomorphic xanthoastrocytoma: a distinctive meningocerebral glioma of young subjects with relatively favorable prognosis. A study of 12 cases. Cancer 1979;44:1839-1852.
• 2. Kleihues P, Burger PC, Scheithauer BW. The new WHO classification of brain tumours. Brain Pathol 1993;3:255-268.
• 3. Perkins SM, Mitra N, Fei W, Shinohara ET. Patterns of care and outcomes of patients with pleomorphic xanthoastrocytoma: a SEER analysis. J Neurooncol 2012;110:99-104.
• 4. Giannini C, Scheithauer BW, Burger PC, et al. Pleomorphic xanthoastrocytoma: what do we really know about it? Cancer 1999;85:2033-2045.
• 5. Whittle IR, Gordon A, Misra BK, Shaw JF, Steers AJ. Pleomorphic xanthoastrocytoma. Report of four cases. J Neurosurg 1989;70:463-468.
• 6. Yu S, He L, Zhuang X, Luo B. Pleomorphic xanthoastrocytoma: MR imaging findings in 19 patients. Acta Radiol 2011;52:223-228.
• 7. Tien RD, Cardenas CA, Rajagopalan S. Pleomorphic xanthoastrocytoma of the brain: MR findings in six patients. AJR Am J Roentgenol 1992;159:1287-1290.
• 8. Nakamura M, Chiba K, Matsumoto M, Ikeda E, Toyama Y. Pleomorphic xanthoastrocytoma of the spinal cord. Case report. J Neurosurg Spine 2006;5:72-75.
• 9. Neal MT, Ellis TL, Stanton CA. Pleomorphic xanthoastrocytoma in two siblings with neurofibromatosis type 1 (NF-1). Clin Neuropathol 2012;31:54-56.
• 10. Lach B, Duggal N, DaSilva VF, Benoit BG. Association of pleomorphic xanthoastrocytoma with cortical dysplasia and neuronal tumors. A report of three cases. Cancer 1996;78:2551-2563.
• 11. Hattab EM, Martin SE, Shapiro SA, Cheng L. Pleomorphic xanthoastrocytoma and oligodendroglioma: collision of 2 morphologically and genetically distinct anaplastic components. J Neurosurg 2011;114:1648-1653.
• 12. Marton E, Feletti A, Orvieto E, Longatti P. Malignant progression in pleomorphic xanthoastrocytoma: personal experience and review of the literature. J Neurol Sci 2007;252:144-153.
• 13. Passone E, Pizzolitto S, D'Agostini S, et al. Non-anaplastic pleomorphic xanthoastrocytoma with neuroradiological evidences of leptomeningeal dissemination. Childs Nerv Syst 2006;22:614-618.
• 14. Gonçalves VT, Reis F, Queiroz LS, França Jr M. Pleomorphic xanthoastrocytoma: MRI findings in a series of cases with histopathological confirmation. Arq Neuropsiquiatr 2013;71:35-39.
• 15. Ng WH, Lim T, Yeo TT. Pleomorphic xanthoastrocytoma in elderly patients may portend a poor prognosis. J Clin Neurosci 2008;15:476-478.

Publication Dates

• Publication in this collection
  16 Jan 2013
• Date of issue
  Jan 2013