1Department of Pathology & Molecular Medicine, Hamilton Health Sciences, McMaster University, Hamilton, Ontario, Canada
This 70-year old lady developed progressive headaches, slight balance problems and occasional word-finding difficulty. On admission MRI showed a poorly demarcated, slightly enhancing lesion in the left cerebellar hemisphere, extending to the cerebellar peduncle and pons. Stereotactic biopsy revealed patternless accumulation of uniformly small cells with clear cytoplasm, minimal hyperchromasia, and few mitoses. The cells were focally positive for S100 and showed MIB-1 activity in approximately 7-10% of the population. The tumour was negative for GFAP, synaptophysin and epithelial markers as well as T-cells and B-cells markers. The lesion was diagnosed as a possible low grade oligodendroglioma. However, 1p/19q deletion testing showed no mutation. Despite radiotherapy and chemotherapy for oligodendroglioma, the tumour was enlarging, infiltrating the remaining part of the cerebellar hemisphere and extending to the midbrain. Due to the tumour progression and increase in intracranial pressure, the neoplasm was partially resected. Immunohistochemistry again was negative for glial, neuronal and epithelial markers, as well as T-cells and B-cells. During the terminal stage of disease she developed severe psychiatric problems. She had no clinical signs of other organ involvement.
Hematopathology consultants excluded malignancy, while the oncologist concluded that this was a case of glioblastoma and elected palliative care only. The family suggested a post-mortem examination. However, the oncologist concluded that autopsy would not produce significant new information.
Material Submitted: MRI few days before surgery and a scan of H&E stained specimen from the resected tumour.
Question to answer: Diagnosis