Home >> Neurological Research, Volume 30, Number 9

Magnetic resonance imaging characteristics of pilomyxoid astrocytoma

Authors: Komotar, Ricardo1; Zacharia, Brad1; Sughrue, Michael2; Mocco, J.1; Carson, Benjamin3; Tihan, Tarik4; Otten, Marc1; Burger, Peter5; Garvin, James6; Khandji, Alexander7; Anderson, Richard1

Source: Neurological Research, Volume 30, Number 9, November 2008 , pp. 945-951(7)

Publisher: Maney Publishing

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Abstract:

Objective: Pilomyxoid astrocytoma (PMA) is a recently identified pediatric low-grade neoplasm that was previously classified as pilocytic astrocytoma (PA), yet demonstrates unique histological features and more aggressive behavior. These tumors have been shown to have significantly shorter progression-free and overall survival probability than classical low-grade astrocytomas, as well as a high rate of cerebrospinal fluid (CSF) dissemination. This paper describes the radiographic features of PMA.

Methods: Magnetic resonance imaging (MRI) was obtained for ten PMAs. Radiographic characteristics of the tumor were recorded in each case. All tissue samples were independently reviewed for confirmation of pathologic diagnosis.

Results: All tumors appeared well-circumscribed with no evidence of peritumoral edema or parenchymal infiltration on MRI. All tumors except one originated from the midline of the neuroaxis. Specifically, five tumors (50.0%) were located in the hypothalamic region, two (20.0%) were located in the spine, two (20.0%) were located in the dorsal brainstem and one was located in the right thalamus. Five tumors (50.0%) demonstrated solid composition, with the remaining five showing some cystic components. Mass effect, hydrocephalus and central necrosis were observed in 62.5, 50.0 and 0.0% of cases, respectively. Eight tumors (80%) were hyperintense on T1-weighted MRI. Seven tumors (77.8%) were hyperintense on T2-weighted MRI. All tumors were hyperintense on fluid attenuated inversion recovery (FLAIR) sequence and hypointense on diffusion weighted imaging (DWI). Upon contrast administration, six tumors (60.0%) enhanced heterogeneously and four tumors (40.0%) enhanced homogenously.

Conclusion: Pilomyxoid astrocytoma is a well-circumscribed pediatric neoplasm that commonly originates from the midline of the neuroaxis and lacks peritumoral edema or central necrosis. It is critical to recognize the predominantly solid and well-circumscribed nature of the neoplasm to avoid confusion with an infiltrating astrocytoma.

Keywords: PILOMYXOID; RADIOLOGY; ASTROCYTOMA; PILOCYTIC; MAGNETIC RESONANCE IMAGING

Document Type: Research Article

DOI: http://dx.doi.org/10.1179/174313208X322806

Affiliations: 1: Department of Neurosurgery, Columbia University, New York, NY, USA 2: Department of Neurosurgery, University of California, San Francisco, CA, USA 3: Department of Neurosurgery, The Johns Hopkins University, Baltimore, MD, USA 4: Department of Pathology, University of California, San Francisco, CA, USA 5: Department of Pathology, The Johns Hopkins University, Baltimore, MD, USA 6: Department of Pediatrics, Columbia University, New York, NY, USA 7: Department of Radiology, Columbia University, New York, NY, USA

Publication date: 2008-11-01

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