Pilomyxoid astrocytoma: a review

Abstract

Pilomyxoid astrocytoma (PMA) is a recently described type of brain tumor. PMA shares similar features with pilocytic astrocytoma (PA), the most common central nervous system (CNS) tumor in the pediatric population, yet displays subtle histologic differences. Previous studies have shown PMA to behave more aggressively than PA, with shorter progression-free and overall survival as well as a higher rate of recurrence and CNS dissemination. These findings suggest that PMA may be a unique and distinct neoplasm. This review summarizes the histologic, clinical, and radiographic characteristics of PMA. In addition, the current treatment options and research endeavors involving this disease are described. Increased recognition of PMA within the medical community has the potential to affect the treatment and prognosis of pediatric low-grade astrocytomas.

Figure 1

(A) Histologic appearance of a typical pilocytic astrocytoma (PA). The tumor demonstrates a biphasic pattern, with compact and loose areas. There is no particular predilection of tumor cells for an angiocentric arrangement. The tumor demonstrates a moderate degree of nuclear variability (original magnification, x200). (B) Histologic appearance of a typical PA, with high-power magnification of the compact area. The tumor cells are arranged in a haphazard manner. Numerous Rosenthal fibers can be identified in this field (original magnification, x400). (C) Histologic appearance of a pilomyxoid astrocytoma (PMA). The tumor is composed of monomorphous bipolar astrocytic cells in a rich myxoid background, with prominent increases in cell density around vascular structures, ie, an angiocentric pattern (original magnification, x200). (D) Histologic appearance of a PMA, with high-power magnification of the perivascular arrangement of tumor cells (angiocentric pattern) and the myxoid background. The tumor cells often exhibited dark condensed chromatin (original magnification, x400). Reprinted with permission from Komotar et al. Pilocytic and pilomyxoid hypothalamic/chiasmatic astrocytomas. Neurosurgery. 2004;54:72-79; discussion 79-80.

Figure 2a

Kaplan-Meier curve comparing the progression-free survival (PFS) of patients with PMA and PA in age-matched cohorts. The mean PFS for PMA and PA cohorts was 25 (SE = 6) and 163 (SE = 31) months, respectively (P < .01). Reprinted with permission from Komotar et al. Pilocytic and pilomyxoid hypothalamic/chiasmatic astrocytomas. Neurosurgery. 2004;54:72-79; discussion 79-80.

Figure 2b

Kaplan-Meier curve comparing the overall survival (OS) of patients with PMA and PA in age-matched cohorts. The mean OS for PMA and PA cohorts was 60 (SE = 10) and 233 (SE = 26) months, respectively (P < .001). Reprinted with permission from Komotar et al. Pilocytic and pilomyxoid hypothalamic/chiasmatic astrocytomas. Neurosurgery. 2004;54:72-79; discussion 79-80.

Figure 3

(A) T1-weighted sagittal image showing a large midline suprasellar mass that is solid in nature and isointense to brain parenchyma. The mass fills the third ventricle and extends to the level of the cerebral aqueduct. Hydrocephalus involving the lateral ventricles is also demonstrated. (B) Fluid-attenuated inversion-recovery sagittal image shows the lesion to be relatively hyperintense with well-defined margins.

Figure 4

Homepage of the Columbia University Pilomyxoid Astrocytoma Resource. This Web site is designed to educate patients and their families as well as enable them to contribute toward PMA research by joining our patient registry.