Gangliogliomas are rare tumors of the central nervous system. We report two unusual cases of gangliogliomas located in the cerebellopontine angle (CPA).

The first patient was a 57-year-old woman, who presented with dizziness and harbored a non-enhanced heterogeneous mass located in the cisternal space of the CPA. A partial microsurgical removal was performed, and the pathological examination concluded a grade I ganglioglioma according to the WHO Classification. The postoperative course was uneventful without any adjuvant treatment and the 5-year imaging follow-up indicated a stable remnant tumor. The second patient was a 35-year-old male who presented with acute vertigo and imbalance associated with recent prominent headaches; MR imaging showed a large heterogeneous and post-contrast enhanced tumor mass located in the CPA cistern with a mass effect on the brain. An optimal subtotal surgical resection was performed. The pathologists concluded a WHO grade III ganglioglioma. In spite of adjuvant radiotherapy and chemotherapy, the evolution proved unfavorable and patient died from cancer complications within a 2-year period. In both cases, the precise origin of the tumor could not be clearly identified even if the major component was present in the cisternal space.

Gangliogliomas growing into the cisternal spaces are exceedingly rare particularly in the CPA. Due to its infiltrating behavior and major difficulties to identify the tumor margins, total resection is not routinely feasible. The histological grading is the most important predictor for oncological prognosis.