Brain, Hemangiopericytoma, H&E stain

Hemangiopericytoma (HPC) is a mesenchymal fibroblastic type neoplasm which is on a histological spectrum that also includes solitary fibrous tumours. Most HPCs are characterized by gene fusion of NAB2 and STAT6. STAT6 immunohistochemistry can be used to confirm the diagnosis. In the CNS, the tumours are typically dural based.

While solitary fibrous tumours have a generally benign behaviour (WHO grade 1), HPCs are often associated with a higher recurrence rate and may develop extracranial metastasis (WHO grade 2-3, based on mitotic activity). As seen in this example, HPCs are relatively cellular tumours demonstrating a “patternless” or short fascicular architecture composed of uniform round to oval nuclei with minimal nuclear pleomorphism. The presence of delicate branching “staghorn” vessels is a characteristic feature.

Reticulin demonstrates a prominent network of fibres investing individual cells. HPCs are often diffusely positive for CD34 and STAT6.

This slide shows H&E stain. See related content for CD34 and reticulin stains.