Pilocytic Astrocytoma

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,


Surgical resection

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