Pilocytic and pilomyxoid hypothalamic/chiasmatic astrocytomas
Ricardo J Komotar1, Peter C Burger, Benjamin S Carson
1Department of Neurosurgery, Columbia University College of Physicians and Surgeons, New York, New York, USA.
Insights
Pilomyxoid astrocytomas (PMAs) are aggressive pediatric brain tumors distinct from pilocytic astrocytomas (PAs). PMAs occur in younger children and have significantly worse progression-free and overall survival rates.
Area of Science:
- Pediatric neuro-oncology
- Neurosurgery
- Pediatric pathology
Background:
- Pilocytic astrocytoma (PA) is a common pediatric brain tumor with generally good outcomes.
- A subset of tumors previously classified as PAs exhibit distinct histological features and aggressive behavior.
- These aggressive neoplasms are now recognized as pilomyxoid astrocytomas (PMAs).
Purpose of the Study:
- To describe the clinicopathological features of pilomyxoid astrocytomas (PMAs).
- To differentiate PMAs from typical pilocytic astrocytomas (PAs).
- To compare outcomes between PMA and PA patient cohorts.
Main Methods:
- Retrospective analysis of 42 PA and 21 PMA cases.
- Comparison of patient demographics, treatment, progression-free survival (PFS), and overall survival (OS) using nonparametric tests.
- Age-matched cohort analysis was performed.
Main Results:
- PMAs occurred in a significantly younger population (mean age 18 months) compared to PAs (mean age 58 months).
- PMAs demonstrated significantly shorter PFS (26 months) and OS (63 months) than PAs (PFS 147 months, OS 213 months).
- Higher recurrence rates (76% for PMAs vs. 50% for PAs) and cerebrospinal fluid dissemination were observed in PMAs.
Conclusions:
- Hypothalamic/chiasmatic PMAs present in younger children and have substantially poorer PFS and OS than typical PAs.
- Distinguishing PMAs from PAs is crucial for accurate prognosis and treatment planning in pediatric astrocytomas.
- Increased recognition of PMAs may improve management strategies and patient outcomes.
Objective:
Pilocytic astrocytoma (PA) is a common type of pediatric brain tumor that can arise within the hypothalamic/chiasmatic region and typically has an excellent outcome. We identified a group of tumors, previously classified as PAs, with unique histological features and aggressive behavior. This article describes the clinicopathological features of these unusual neoplasms, which are currently known as pilomyxoid astrocytomas (PMAs), to better differentiate them from typical PAs.
Methods:
Medical information and surgical specimens were obtained for 42 PA cases and 21 PMA cases. Patient demographic features, treatment modalities, progression-free survival (PFS) times, overall survival (OS) times, and outcomes were compared between the groups with nonparametric tests.
Results:
The PMA group included 12 male and 9 female patients. The PA group included 27 male and 15 female patients. The mean ages at diagnosis for the PMA and PA groups were 18 months (range, 2-84 mo) and 58 months (range, 4-189 mo), respectively (P < 0.01). The mean PFS times for the PMA and PA groups were 26 and 147 months, respectively (P < 0.001). The mean OS times for the PMA and PA groups were 63 and 213 months, respectively (P < 0.001). Sixteen patients with PMAs (76%) experienced local recurrence, and three of those patients demonstrated evidence of cerebrospinal fluid dissemination. Twenty-one patients with PAs (50%) experienced local recurrence, none with evidence of cerebrospinal fluid dissemination. Within the follow-up period, seven patients with PMAs (33%) and seven patients with PAs (17%) died as a result of their disease. In an age-matched set, the mean PFS times for the PMA and PA groups were 25 and 163 months, respectively (P < 0.01), and the mean OS times for the PMA and PA groups were 60 and 233 months, respectively (P < 0.001).
Conclusion:
Hypothalamic/chiasmatic PMAs occurred in a significantly younger population and were associated with substantially shorter PFS and OS times than were typical PAs. Increased recognition of these lesions could affect the prognosis and treatment of pediatric astrocytomas.
