Intraventricular pilocytic astrocytoma in an adult patient
Joshua Hendrix1, Zhenggang Xiong1
1Department of Pathology and Laboratory Medicine, Robert Wood Johnson Medical School, Rutgers University, NJ, USA.
Insights
Pilocytic astrocytoma, a rare adult brain tumor, presented as a third ventricle mass causing obstructive hydrocephalus. This case highlights the importance of considering pilocytic astrocytoma in adult intraventricular brain neoplasms.
Area of Science:
- Neuro-oncology
- Neuropathology
Background:
- Pilocytic astrocytomas (PAs) are typically pediatric central nervous system tumors, predominantly affecting midline structures.
- Intraventricular PAs in adults are exceptionally rare, posing diagnostic challenges.
Observation:
- A 38-year-old woman presented with obstructive hydrocephalus due to a third ventricle brain tumor.
- Histopathology revealed a biphasic pattern with Rosenthal fibers and microcystic areas, lacking mitosis or necrosis.
- Immunohistochemistry showed GFAP, Olig2, and ATRX positivity, with negative NeuN and EMA. Ki67 index was <1%.
Findings:
- Molecular analysis excluded IDH and H3F3A mutations.
- The tumor's characteristics were consistent with pilocytic astrocytoma.
- This case represents an adult pilocytic astrocytoma originating in the third ventricle.
Implications:
- Pilocytic astrocytoma should be included in the differential diagnosis for adult intraventricular brain neoplasms.
- This finding expands the known clinical presentations of pilocytic astrocytoma.
- Highlights the need for comprehensive diagnostic evaluation in rare adult CNS tumors.
Abstract:
Pilocytic astrocytomas are tumors of the central nervous system mostly during the first two decades of life. Although they are mostly common in the midline structures of children, pilocytic astrocytoma within the ventricular system of an adult is extremely rare. We report a case of a 38-year old woman with obstructive hydrocephalus secondary to a brain tumor within the third ventricle. On histological examination, the tumor exhibited biphasic growth pattern comprising compacted cellular areas with Rosenthal fibers and loose textured microcystic areas with eosinophilic granular bodies. Mitosis or necrosis was not present. Immunohistochemical studies demonstrated glial fibrillary acid protein (GFAP), Olig2, and ATRX positivity as well as NeuN and EMA negativity. Ki67 labeling index was less than 1%. Molecular studies revealed that there are no isocitrate dehydrogenase (IDH) gene mutation and H3F3A mutation. This clinical presentation along with the histologic and molecular findings is consistent with a pilocytic astrocytoma arising in the third ventricle of this adult brain, which indicates that pilocytic astrocytoma can present as an intraventricular tumor in an adult patient and should be routinely included in the differential diagnosis of intraventricular brain neoplasm.
