Title: 52 year-old woman with progressive headaches and ataxia

Author: Dimitri Trembath, MD, PhD

Institution: Foundation Medicine, Morrisville, North Carolina 

Clinical History: A 52-year-old woman presented with a six-month history of progressively worsening headaches. Her course was notable for intermittent visual disturbances and a recent onset of mild ataxia. There was no reported history of malignancy or prior neurologic disease. 

Radiology: Magnetic resonance imaging demonstrated a 3.5 cm well-circumscribed, contrast-enhancing extra-axial mass centered in the cerebellopontine angle. The lesion showed a broad-based dural attachment. 

Representative Histology / IHC: 

Questions for Viewers: 

1) What is the differential diagnosis for this lesion? 

2) What immunohistochemical stains would help with the differential diagnosis? 

3) What are likely molecular altercations found in this lesion?