Pilomyxoid Astrocytoma
Pilomyxoid astrocytoma (PMA)
- Aggressive variant of pilocytic astrocytoma (PA) that arises from the sellar (chiasmatic) or hypothalamic region.
- They are solid tumors with homogenous contrast enhancement.
- PMA do NOT have large cysts (unlike pilocytic astrocytoma (PA), which do).
- They tend to encase key basal cerebrovasculature (ie, vessels at/near the Circle of Willis).
- Pathology: PMA pathology is similar to PA but WITHOUT Rosenthal fibers and eosiniphilic granular bodies
- If you see a myxoid background with biphasic compact and loose architecture with elongated cell process but NO Rosenthal fibers or eosiniphilic granular bodies, think: PMA.
- Prognosis: PMA prognosis is worse than PA (which can be multiple decades) but not as bad as grade 3 astrocytomas.
- introduced in the 2007 WHO classification of tumors as a grade 2 but dropped from the more recent, 2016 WHO grading classification.
References
- Adesina, Adekunle M., Tarik Tihan, Christine E. Fuller, and Tina Young Poussaint. Atlas of Pediatric Brain Tumors. Springer, 2016.
- Louis, David N., Arie Perry, Guido Reifenberger, Andreas von Deimling, Dominique Figarella-Branger, Webster K. Cavenee, Hiroko Ohgaki, Otmar D. Wiestler, Paul Kleihues, and David W. Ellison. “The 2016 World Health Organization Classification of Tumors of the Central Nervous System: A Summary.” Acta Neuropathologica 131, no. 6 (June 1, 2016): 803–20. https://doi.org/10.1007/s00401-016-1545-1.
- Marvin 101. English: Histopathology of Rosenthal-Fibres. H&E Staining Showing These Elongated Eosinophilic Structures in a Case of Pilocytic Astrocytoma. Magnification 400x. January 22, 2009. Own work. https://commons.wikimedia.org/wiki/File:Rosenthal_HE_40x.jpg.
- Newton, Herbert B. Handbook of Brain Tumor Chemotherapy, Molecular Therapeutics, and Immunotherapy. Academic Press, 2018.
- Orkin, Stuart H., David E. Fisher, A. Thomas Look, Samuel Lux, David Ginsburg, and David G. Nathan. Oncology of Infancy and Childhood E-Book. Elsevier Health Sciences, 2009.
- Perry, Arie. “WHO’s Arrived in 2016! An Updated Weather Forecast for Integrated Brain Tumor Diagnosis.” Brain Tumor Pathology 33, no. 3 (July 1, 2016): 157–60. https://doi.org/10.1007/s10014-016-0266-4.