Pleomorphic xanthoastrocytoma with anaplastic features in a child

Clinical History

We present the case of a 9-year-old girl who came to our centre after a first episode of epileptic seizure. The crisis was preceded by headache of some minutes’ duration. She had no previous relevant medical antecedents.

Imaging Findings

Initially the child underwent a CT examination without contrast, which showed a heterogeneous parenchymal lesion with mild vasogenic oedema and higher attenuation areas suggesting possible haemorrhagic deep component. Bone scalloping was easily recognized evaluating the bone window.
MRI was performed, showing a mass with ill-defined margins in the right parietal lobe. Superficial small clustered cystic areas were observed reaching the cortical parenchyma with deeper white matter extension. Evident meningeal involvement was noticed after contrast medium injection.

Discussion

Pleomorphic xanthoastrocytoma (PXA) is a primary brain tumour that occurs in children and young adults, usually in the first three decades of life. It is considered to have a glial origin arising from subpial astrocytes, comprising less than one percent of astrocytomas [1]. That´s why it is mostly located in the superficial brain cerebral parenchyma and usually involves cortical and leptomeninges, although in some cases it can grow deeply in the brain. Temporal lobes are the most frequent locations followed by parietal and frontal lobes; sometimes it can grow in the thalamus, cerebellous, spinal cord, retina, sellar and pineal region [1]. Recently a new type of pleomorphic xanthoastrocytoma with anaplastic features has been proposed. It is a special type of PXA with high mitotic activity (more than 5 mitosis/10 hpf) and areas of necrosis which are not typical of PXA [2].
Dizziness, headache and seizures are usually the clinical presentation in children, adolescents and young adults. Syncopal episodes and visual disturbances have also been described as initial clinical manifestations [3].
PXA are more often superficially-located supratentorial masses. Meningeal involvement is typical of PXA and inner table scalloping is frequent. Though they can be only solid, they more usually have a cystic component or present as predominantly cystic masses with mural solid nodules. Their solid components are hypo or isointense on T1 and slightly hyperintense on T2. There is moderate to intense heterogeneous enhancement of solid nodules and thick cystic walls. Their margins can be either well-delimited or undefined [4].
Vasogenic surrounding oedema can be present in variable quantity. Haemorrhage can be present in one third of the cases. Calcifications are not usually found but do not exclude the diagnosis.
DWI can reveal relatively lower ADCs values and ratios of the solid components than other low-grade tumours [5].
PXA is a low-grade tumour with a good prognosis. However, XPA with anaplastic features (up to 20% of PXA will undergo anaplastic transformation) has a worse prognosis because it is associated with parenchymal invasion, necrosis, perivascuar space involvement and thus higher recurrence index after surgery.
Mitotic index and total surgery excision are the two most important factors for prognosis.
Surgery is the main treatment for XPA. Radiotherapy and chemotherapy can be considered in patients with uncomplete resections or with anaplastic features.
As radiologist, we should consider the diagnosis of XPA in a child or young person with a predominantly cystic superficial cerebral mass with heterogeneous enhancement and especially in addition with meningeal involvement and scalloping of the inner table skull.

Differential Diagnosis List

Final Diagnosis

Pleomorphic xanthoastrocytoma

URL:	https://eurorad.org/case/12781
DOI:	10.1594/EURORAD/CASE.12781
ISSN:	1563-4086