Case contributed by Assoc Prof Frank Gaillard


Adult patient presenting with a skull mass.

Patient Data

Age: Adult

MRI demonstrates a very large extra-axial mass eroding through the bone. It vividly enhances and had large feeding vessels around the margins. There is no evidence of invasion into the brain. 

Case Discussion

Features are consistent with a hemangiopericytoma. The diagnosis was confirmed after resection. 


Microscopic Description:

Sections show a densely cellular neoplasm composed of closely packed, randomly oriented cells interspersed by numerous slit-like vascular channels. Scattered through are several wide and branching thin-walled channels with a "staghorn" appearance. The tumor cells have scant cytoplasm with ill-defined borders and display oval, plump, or elongated nuclei with evenly dispersed chromatin. Only a few mitotic figures are identified. MIB-1 immunostaining shows only a few scattered cells with positive nuclei. Throughout the tumor are patches of hypocellularity. The reticulin stain shows a rich reticulin network that often typically invests individual cells. There are no anaplastic features such as necrosis or high mitotic activity. The tumor cells are strongly positive for vimentin and negative for EMA and S-100. There is patchy strong immunoreactivity of the tumor cells for CD34. Endothelial cells lining the sinusoidal vessels are strongly positive for both Factor-VIII-R:Ag and CD34. The tumor is firmly attached to the dura. In sections B9 and B14, small fragments of bone are incorporated within the tumor, indicating bone invasion. Frequently encountered throughout the tumor are mast cells.

Final Diagnosis: hemangiopericytoma.

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Case information

rID: 4326
Published: 9th Aug 2008
Last edited: 26th Jan 2021
Inclusion in quiz mode: Included

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