Clinical Summary

A 19-month-old left-hand dominant female was found to have a mass in the left frontoparietal lobe with concern for diffuse leptomeningeal involvement for which surgical resection was undertaken. Despite also undergoing an extensive regimen of chemotherapy, a recurrence was detected along the anterior aspect of the resection cavity 3 years later. Repeat excision was undertaken followed by radiation to the tumour bed. Following the second surgery, she was left with right-sided hemiplegia and hemiparesis.

At 19 years of age (approximately 15 years later), she began experiencing multiple 3-minute episodes of sudden repetitive horizontal eye movement, breathlessness, and facial droop, occasionally preceded by light-headedness and double vision. She was diagnosed with focal epilepsy which proved to be drug-resistant. Electroencephalography identified epileptogenic foci arising from the left frontoparietal resection cavity. Prompted by this, the clinician requests a retrospective review of the pathological diagnoses.

Discussion points

1. What is the differential diagnosis?

2. What special stains, IHCs, or ancillary testing would be most informative?