WHO grade I neoplasm
Suggested by MRI and confirmed by pathology (brain biopsy/resection)
Findings on investigations:
- Cerebellar (commonest site). May occur in optic nerves, hypothalamus, thalamus. Brain stem-tectal plate. Ill defined cystic tumor with solid component. Occasionally without cyst.
- T1: low signal, enhancement of wall and solid components
- T2: high intensity
Histology: astrocytes with bipolar processes, eosinophilic processes (long tapering), oval nuclei, Rosenthal fibres (eosinophilic irregular fibres), eosinophilic granular bodies (PAS positive). Vessels are prominent. Compact areas & loose (microcyts) areas. Oligodendrocyte-like cells & infarct like necrosis may occur.
Immunohistochemistry: GFAP positive, S100 positive,