Brain Pathology Case of the Month - December 2016

Contributed by Tafadzwa Mandiwanza MRCS1, Chandrasekaran Kaliaperumal FRCS1, Linda Mulligan FRCPath2, Elizabeth Ryan FFR RCSI3, Seamus Looby FFR RCSI3, John Caird FRCS1, Francesca Brett MD., FRCPath., MSc (FM)2,
1Pediatric Neurosurgery Department, Children's University Hospital, Temple Street, 2Neuropathology Department, Beaumont Hospital, Beaumont Road, 3Radiology Department, Beaumont Hospital, Beaumont Road, Dublin 9, Ireland


A 3-year-old boy initially presented in January 2010, with a 4-month history of progressive right hemiparesis. Developmentally his motor skills had been somewhat delayed, with walking only at 18 months while dragging his right leg and a left hand preference from an early age. Initial MRI revealed a large left thalamic enhancing partly cystic-solid lesion involving the left posterior limb of the internal capsule and the posterior lentiform, with mass effect on the third ventricle and brainstem (Figure 1, T1 post contrast) (Figure 2, T2) (Figure 3, FLAIR). MRI of the spine was normal.

He had near total surgical resection with intraoperative neurophysiology monitoring. On immediate post-operative MRI, two small enhancing areas were noted, one adjacent to the left middle cerebral artery (MCA) and one deep within the resection cavity (Figure 4, T1 post contrast). He had residual right hemiparesis post operatively and did not require any further treatment other than regular physiotherapy with no improvement in the hemiparesis.

Surveillance scans at 5, 11 and 18 months were stable. At 24 and 27 months a rim enhancing lesion appeared. Non contrast CT at 30 months showed a rounded hyperattenuated lesion in the left temporal lobe (Figure 5). Given the radiological appearances, the presumptive diagnosis was of tumor progression with possible malignant transformation. He was readmitted for a further resection. A pre-operative MR raised the possibility that the more superficial sylvian fissure lesion could represent an aneurysm or pseudoaneurysm. CT angiogram showed no enhancement in this lesion (Figure 6). Four-vessel angiogram was normal (Figure 7).

The patient was admitted for a resection of these lesions during which a solid nodule attached to the M2 of the left MCA segment was removed and labeled Specimen A. The tumor cavity was carefully resected; however part of the capsule was adherent to the midbrain and this was left behind. This tissue was labeled Specimen B and washings from the CUSA were labeled Specimen C. Post-operative MR scan demonstrated an absent M2 segment of the left MCA and no enhancing areas. The patient was well post-operatively with no worsening of his preexisting hemiparesis.


Grossly, specimen A was noted to be a solid nodule measuring 1 cm in diameter while specimen B and C were of pale gelatinous material. Specimen B and C histology had fragments of a tumor similar to the original resection (Figure 8). Sections of specimen A showed abnormal giant cells (Figure 9) surrounding polarizable material (Figure 10). What are your diagnoses?


International Society of Neuropathology