Pleomorphic xanthoastrocytoma (PXA) is a rare glioma. This paper aimed to analyze magnetic resonance imaging (MRI) characteristics in a series of patients diagnosed with PXA. We analyzed MRI findings in 9 patients with histopathologic diagnosis of PXA in our department over the last 12 years. The mean age of patients was 27.3 years. Cortical location was observed in all cases. The lesion imaging was solid-cystic in six cases. In eight cases, the solid component presented hypo or isointense on T1 and iso or hyperintense on T2. Contrast enhancement in the solid component was observed in eight cases. The observed imaging pattern of PXA was superficial location with leptomeningeal involvement, solid-cystic pattern and contrast enhancement in the solid component. We should consider that the association between PXA and other cortical tumors may occur, particularly, with gangliogliomas, which tend to be the main differential diagnosis in MRI.Key words: magnetic resonance imaging, central nervous system, astrocytoma.
RESUMOXantoastrocitoma pleomórfico (PXA) é um glioma raro. Este estudo teve como objetivo analisar aspectos de imagem por ressonância magnética (RM) de uma série de pacientes com diagnóstico de PXA. Foram analisados exames de RM de 9 pacientes com diagnóstico histopatológico de PXA nos últimos 12 anos. A média de idade dos pacientes foi de 27,3 anos. Localização cortical foi observada em todos os casos. Padrão sólido-cístico foi observado em seis casos. Em oito casos, o componente sólido apresentou-se hipo ou isointenso em T1 e iso ou hiperintenso em T2. Foi observada captação de contraste na porção sólida em oito casos. O padrão de imagem observado do PXA foi de localização superficial com envolvimento leptomeníngeo, padrão sólido-cístico e captação de contraste pelo componente sólido. Devemos considerar que a associação entre PXA e outros tumores corticais pode ocorrer, particularmente, com ganglioglioma, que tende a ser o principal diagnóstico diferencial em RM.Palavras-Chave: imagem por ressonância magnética, sistema nervoso central, astrocitoma.
The patient was a 15-year-old male with seizures. Diagnostic imaging demonstrated a solid-cystic expansive lesion, centered on the white matter of the left temporooccipital paratrigonal region, with growth into the ventricular system (Fig 1). Histological analysis led to the diagnosis of pleomorphic xanthoastrocytoma (PXA) (Fig 2). PXA is classically a tumor with a predilection for superficial growth affecting young adults, and is rarely seen in paratrigonal/intraventricular locations. The tumor in this case may have arisen in and around the ventricle or from subcortical white matter. The patient has now been followed for ten years. The tumor recurred after five years without anaplastic transformation. He appears to be free of disease at present.
A nine year-old male had refractory seizures for four years. Diagnostic imaging (Fig 1A and B) demonstrated a cortico-subcortical focal lesion at the isthmus of the right cingulate gyrus. Biopsy yielded diagnosis of ganglioglioma (Fig 2A). Reoperation one year later showed similar features, but included atypical and multinucleated cells (Fig 2B).At the age of 13, the patient had symptom recurrence. Diagnostic imaging (Fig 1C and D) demonstrated a heterogeneous enhanced lesion in the right parietal region, with necrosis. Histology (Fig 2C to F) revealed a malignant glial tumor with the appearance of glioblastoma multiforme. A few tumor cells were positive for chromogranin. A diagnosis of malignant transformation of ganglioglioma was made.Gangliogliomas are rare tumors predominating in the early decades of life, with strong association with long term intractable epilepsy [1][2][3] . They are composed of variable proportions of glial (mainly astrocytic) cells and mature or dysplastic neurons 2 . Malignant change is a rare, but well recognized, complication. Transformation of the glial component from the low grade to a higher grade is observed in most cases. Also, there is a case of malignant transformation secondary to degeneration of the neuronal component into a neuroblastoma 4 . Some reports in literature 5 suggest that radiation may predispose to malignant degeneration. In this case, the patient did not receive postoperative radiation.
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