Pleomorphic xanthoastrocytoma

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Sujit Routray, M.D. [2]

Synonyms and keywords: Pleomorphic xanthoastrocytomas; PXA

Overview

Pleomorphic xanthoastrocytoma is a type of rare, low-grade astrocytoma (WHO Grade II) found among young patients who typically present with temporal lobe epilepsy.[1]

Pathophysiology

Pathogenesis

Gross Pathology

  • On gross pathology, polymorphic xanthoastrocytoma is characterized by a well-circumscribed mass, often with a cystic component and a superficially situated mural nodule.[3]
  • Polymorphic xanthoastrocytomas are almost invariably (98%) located supratentorially, typically involving the cortex and overlying leptomeninges. Approximately half are located in the temporal lobe.
  • They are found commonly in the area of the temporal lobe, frontal lobe, or superior to the parietal lobe. In about 20% of cases, more than one lobe is involved.[4]

Microscopic Pathology

  • On microscopic histopathological analysis, polymorphic xanthoastrocytoma is characterized by:[3][5]
  • Ill-defined margins
  • Spindle cells, polygonal cells, multi-nucleated cells, and lipid laden xanthomatous astrocytes
  • Pleomorphic nuclei
  • No endothelial proliferation or necrosis

Immunohistochemistry

Differentiating Pleomorphic Xanthoastrocytoma from other Diseases

Pleomorphic xanthoastrocytoma must be differentiated from:[5][6]

Diseases Clinical manifestations Para-clinical findings Gold
standard
Additional findings
Symptoms Physical examination
Lab Findings MRI Immunohistopathology
Head-
ache
Seizure Visual disturbance Constitutional Focal neurological deficit
Adult primary brain tumors
pleomorphic-xanthoastrocytoma
+ + +/− +
  • Chicken wire capillary pattern
Oligodendrocytoma + + +/− +
  • Chicken wire capillary pattern
  • Fried egg cell appearance
Glioblastoma multiforme
[7][8][9]
+ +/− +/− +
  • Pseudopalisading appearance
Meningioma
[10][11][12]
+ +/− +/− +
  • Well circumscribed
  • Extra-axial mass
  • Whorled spindle cell pattern
  • May be associated with NF-2
Hemangioblastoma
[13][14][15][16]
+ +/− +/− +
Pituitary adenoma
[17][18][9]
+ Bitemporal hemianopia
  • It is associated with MEN1 disease.
Schwannoma
[19][20][21][22]
+
  • Split-fat sign
  • Fascicular sign
  • Often have areas of hemosiderin
  • S100+
Primary CNS lymphoma
[23][24]
+ +/− +/− +
  • Single mass with ring enhancement
Childhood primary brain tumors
Pilocytic astrocytoma
[25][26][27]
+ +/− +/− +
Medulloblastoma
[28][29][30]
+ +/− +/− +
  • Homer wright rosettes
Ependymoma
[31][9]
+ +/− +/− +
  • Hydrocephalus
  • Causes an unusually persistent, continuous headache in children.
Craniopharyngioma
[32][33][34][9]
+ +/− + Bitemporal hemianopia +
Pinealoma
[35][36][37]
+ +/− +/− + vertical gaze palsy
  • May cause prinaud syndrome (vertical gaze palsy, pupillary light-near dissociation, lid retraction and convergence-retraction nystagmus
Vascular
AV malformation
[38][39][9]
+ + +/− +/−
Brain aneurysm
[40][41][42][43][44]
+ +/− +/− +/−
  • MRA and CTA
Infectious
Bacterial brain abscess
[45][46]
+ +/− +/− + +
  • Central hypodense signal and surrounding ring-enhancement in T1
  • Central hyperintense area surrounded by a well-defined hypointense capsule with surrounding edema in T2
  • History/ imaging
Tuberculosis
[47][9][48]
+ +/− +/− + +
  • Lab data/ Imaging
Toxoplasmosis
[49][50]
+ +/− +/− +
  • History/ imaging
Hydatid cyst
[51][9]
+ +/− +/− +/− +
  • Imaging
CNS cryptococcosis
[52]
+ +/− +/− + +
  • We may see numerous acutely branching septate hyphae
  • Lab data/ Imaging
CNS aspergillosis
[53]
+ +/− +/− + +
  • Multiple abscesses
  • Ring enhancement
  • Peripheral low signal intensity on T2
  • We may see numerous acutely branching septate hyphae
  • Lab data/ Imaging
Other
Brain metastasis
[54][9]
+ +/− +/− + +
  • Based on the primary cancer type we may have different immunohistopathology findings.
  • History/ imaging

ABBREVIATIONS

CNS=Central nervous system, AV=Arteriovenous, CSF=Cerebrospinal fluid, NF-2=Neurofibromatosis type 2, MEN-1=Multiple endocrine neoplasia, GFAP=Glial fibrillary acidic protein, HIV=Human immunodeficiency virus, BhCG=Human chorionic gonadotropin, ESR=Erythrocyte sedimentation rate, AFB=Acid fast bacilli, MRA=Magnetic resonance angiography, CTA=CT angiography

Epidemiology and Demographics

Prevalence

  • Pleomorphic xanthoastrocytoma constitutes approximately 1% of all primary brain tumors.[55]

Age

  • Pleomorphic xanthoastrocytoma is a rare disease that tends to affect children and young adults.[5]
  • The median age at diagnosis is 26 years.[56]

Natural History, Complications and Prognosis

Natural History

If left untreated, patients with pleomorphic xanthoastrocytoma may progress to develop seizures, focal neurological deficits, and malignant transformation to either WHO grade III lesion or glioblastoma multiforme.[57]

Complication

Common complications of pleomorphic xanthoastrocytoma include:[57]

Prognosis

Prognosis is generally good, and the 5-year survival rate of patients with pleomorphic xanthoastrocytoma is approximately 70-80%.[57]

Symptoms

Symptoms of fibrillary astrocytoma include:[58][59]

  • Elevated intracranial pressure
  • Temporal lobe epilepsy
  • Seizures with or without aura
  • Amnesia
  • Loss of consciousness
  • Abnormal auditory sensations (sound or tune)
  • Abnormal gustatory sensation (taste)
  • Abnormal olfactory sensation (smell that is not truly present)
  • Dysphoria or euphoria
  • Motionless staring, automatic movements of the hands or mouth, inability to respond to others, unusual speech, or unusual behavior
  • Neurological symptoms

CT

Head CT scan is helpful in the diagnosis of pleomorphic xanthoastrocytoma. On CT scan, pleomorphic xanthoastrocytoma is characterized by:[60]

  • Iso- or hypoattenuating mass
  • Calcification
  • Vivid enhancement on contrast administration

MRI

Brain MRI is helpful in the diagnosis of pleomorphic xanthoastrocytoma. On MRI, pleomorphic xanthoastrocytoma is characterized by:[60]

MRI Component Findings

T1 weighted image

  • Solid component: iso- to hypointense compared to the gray matter
  • Cystic component: hypointense
  • Leptomeningeal involvement

T2 weighted image

  • Solid component: iso- to hyperintense compared to the gray matter
  • Cystic component: hyperintense
  • Mild surrounding vasogenic edema

T1 weighted image with contrast

  • Solid component: vivid enhancement

Biopsy

Biopsy of pleomorphic xanthoastrocytoma tumor, taken through a needle during a simple surgical procedure, helps to confirm the diagnosis.[61]

Other Diagnostic Studies

Electroencephalogram

  • Electroencephalogram (EEG) is performed among patients of pleomorphic xanthoastrocytoma to record any abnormal electrical activities (seizures).[59]

Digital Subtraction Angiography

Positron Emission Tomography

Treatment

  • The predominant therapy for pleomorphic xanthoastrocytoma is surgical resection. Adjunctive radiation may be indicated in cases of incompletely resected or recurrent tumors.[63][64]
  • Complete surgical resection is often possible. However, the best choice of treatment will depend on many individual factors including:[63]
  • Patient's medical history and overall health condition
  • Type, location, and size of the tumor
  • Patient's age
  • Aggressiveness of the tumor
  • If surgery is performed and the tumor is completely resected, further treatment may not be required.

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