Abstract 3- 0930-0945
Category: Clinical

At the end of the session,
participants will be able to:

  1. The diagnosis of malignant astrocytomas based on molecular features of IDH1 mutation may be unaccompanied by year-over-year tumor growth despite no treatment with either radiation or chemotherapy. 
  2. The neuroimaging of such tumors is not that of a diffuse glioma. 
  3. That binucleate and intermediate glio-neuronal cells by conventional histology and by immunocytochemistry, may favor ganglioglioma. 

 

Presenter

Dr. Roland Auer

Following on an MD at the University of Alberta, Neuropathology training in London, ON, and a PhD in brain damage from Lund, Swede, Dr. Auer has been in a combined clinical-research practice for 36 years now.

Authors

Roland N. Auer 1,5, Egiroh Omene 2, Sarah E. Edwards 1, Kotoo Meguro 1, Daryl R. Fourney 1, Jose F. Tellez-Zenteno 2, Gary R.W. Hunter 2, Kyle Moulton 3, Vijayananda Kundapur 4

Depts of 1Surgery (Neurosurgery), 2Neurology, 3Radiology, 4Oncology, 5Pathology and Laboratory Medicine, University of Saskatchewan, Saskatoon, SK, CANADA

Target Audience:
Pathologists, Residents, Oncologists, Radiologists

CanMEDS:
Medical Experts (the integrating role), Communicator, Collaborator, Leader, Health Advocate, Scholar, Professional

Long term disease-free survival after surgical resection only: malignant IDH-mutated astrocytoma versus ganglioglioma

Abstract

Gangliogliomas are important to distinguish from anaplastic astrocytoma and glioblastoma multiforme, to avoid potentially damaging radiation and for accurate prognostication.  Two patients with a seizure presentation at age 31 and 30, had large, well demarcated brain tumors each 4.3 cm with no suggestion of diffuse glioma on imaging. Both patients requested tumor resection.  The first patient intra-operatively was found to have the tumor in close proximity to the motor cortex, and resection was thus incomplete, leaving residual tumor in situ. The second patient had a gross total resection. An initial diagnosis of ganglioglioma, was changed to malignant astrocytoma based on IDH1 mutation, loss of ATRX, abundant mitoses and a high Ki67 labelling index.  Conventional histology revealed glial, neuronal and intermediate forms in both tumors.  Both patients declined treatment following neurosurgery and remain without tumor growth on neuroimaging at 6 and 3 years later, respectively.  The findings illustrate the conundrum of tumors diagnosed as malignant astrocytomas based on molecular profile, but showing no growth after no treatment, as well as the superiority of resection over needle biopsy, as the first tumor was called a diffuse astrocytoma on a needle biopsy prior to resection. Without diffuse astrocytoma appearing on long-term follow-up in the absence of radiochemotherapy, a diagnosis of diffuse, malignant astrocytoma is increasingly untenable as years pass. Both patients and their clinicians question the malignant diagnosis. Gangliogliomas have been reported with IDH mutation (Brain Pathol 2011; 21: 564-574). Ganglioglioma versus diffuse astrocytoma remains a difficult differential diagnosis in neuropathology.