Meningeal Mesenchymal Tumors Hemangiopericytoma

This rare, malignant (grade 4) tumor, arising from pericites (periendothelial cells) of the blood vessels, is attached to the dura. It has a tendency to invade the brain, recur, and metastasize. It is most common in young adult men.

figure 1 1.29

Hemangiopericytoma showing a high cellularity (A) with small elongated cells (HE) (B) in a rich reticulin network (reticulin stain).

figure 1 1.29

Hemangiopericytoma showing a high cellularity (A) with small elongated cells (HE) (B) in a rich reticulin network (reticulin stain).

Grossly, hemangiopericytoma is circumscribed, firm, round, oval, or lobulated. Histologically, it is highly cellular, composed of uniform polygonal cells arranged in sheets or small groups separated by a rich reticulin meshwork. The cells immunoreact for vimentin and CD34, but not for epithelial membrane antigen. Mitoses are frequent. A rich vascular supply consists of thin branching vessels (staghorn vessels) and sinusoids lined with endothelial cells (Fig. 11.29).

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