Brain Pathology Case of the Month - October 2006

Contributed by Iqroop Chopra, MD MRCS, Federico Roncaroli, MD*, Vasileios Apostolopoulos MD MRCS, Jilly Moss FRCPath**, David Peston FIBMS**, Kevin O’Neill MD FRCS, FRCS-SN
Department of Neurosurgery, *Department of Neuropathology, **Department of Histopathology Charing Cross Hospital London , United Kingdom.
Published on line in October 2006


A 37-year-old man presented with a 2-month history of headache and balance impairment. He also complained of nausea and two episodes of vomiting a few days before admission. His past medical history was unremarkable. Neurological examination showed mild left sided ataxia.


Brain MR-scan showed a heterogeneously enhancing superficial tumor arising from the left cerebellar cortex with a cystic component. The lesion caused vasogenic edema with mass effect on the fourth ventricle (Fig 1 and Fig 2). Evidence of early hydrocephalus with dilatation of temporal horns was present. There was a large draining vessel lateral to the tumor. A pre-operative diagnosis of hemangioblastoma was suggested. The patient underwent posterior fossa craniotomy with complete excision of the tumor. Intra-operatively the lesion appeared well-demarcated from the cerebellar cortex except for its lateral portion wherein there was no cleavage. A large dilated vein on the tumor surface was seen postero-laterally. The patient fully recovered and after 6 months follow-up MR-scans did not show recurrence.


The tumor was well-demarcated from the cerebellar cortex and grew partially extra-axially also filling the subarachnoid space. It showed compact architecture (Fig 3), had a dense vascular network and was composed of cuboidal and columnar cells mostly showing perivascular arrangement (Fig 4). No fibrillary background was present. There were some perivascular pseudorosettes featuring a "cartwheel" appearance that consisted of columnar cells with short cytoplasmic processes and eccentric nuclei (Fig 5). The vascular network was composed of capillaries and medium sized vessels, some of which had thick and fibrotic walls. Mitoses were rare (average 1x30 fields at 400x, Nikon Plan Fluor 40x0.75 mm). No necrosis or endothelial proliferation was present. Most of the neoplastic cells expressed GFAP (Fig 6), S-100 protein and NSE. Immunostains for cytokeratin CAM5.2, cytokeratins AE1/AE3, smooth muscle actin, CD31, EMA, chromogranin and synaptophysin were negative. The Ki67 labeling index was 5%. Ultrastructural examination showed a tumor composed of apposed plump cells surrounding capillaries with grossly thickened basal lamina. Narrow cytoplasmic processes interdigitated between the cells and were in contact with the basal droplets. Cells junctions were primitive and intermediate. Several conspicuous intracytoplasmic whorls of endoplasmic reticulum were present. Intracytoplasmic lumina, ciliary bodies and microvilli were absent.


International Society of Neuropathology