Case of the Month: October 2023

The answer to the October Case of the Month is glioblastoma. Glioblastoma is a high-grade, infiltrative glial neoplasm with key diagnostic features on histology: hypercellularity, nuclear atypia, mitoses, geographic necrosis, and microvascular proliferation. These features differentiate glioblastoma from lower-grade gliomas, though immunohistochemistry and molecular testing are required for final classification and prognostication. Glioblastoma is the most common malignant brain tumour in adults. The peak incidence in patients is age 55-85 years. Prognosis is very poor, with a survival of only 1-2 years after diagnosis. Treatment includes surgical resection, radiation, and chemotherapy. Glioblastomas are highly infiltrative and spread throughout the brain, which makes complete resection impossible.

Brain lesions are often assessed intraoperatively in order to guide surgical management. Pre-operative medical imaging helps narrow the differential diagnosis. For ring-enhancing lesions, the differential diagnosis includes (but is not limited to) glioblastoma, metastatic malignancy, lymphoma, and abscess, all of which need to be treated differently. Intraoperative consultations performed by the pathologist are done by making a smear for cytological evaluation and freezing, cutting, and staining a piece of tissue for histological assessment. The pathologist then looks at the slides in real-time and provides an answer to the neurosurgeon who is waiting in the operative room for the result.