Hemangiopericytomas in the Central Nervous System: A Multicenter Study of Korean Cases with Validation of the Usage of STAT6 Immunohistochemistry for Diagnosis of Disease.

Background: Hemangiopericytoma (HPC) in the central nervous system (CNS) is a rare disease with distinctive biological/clinical characteristics compared with meningioma.

Methods: Cases of HPCs of the CNS were collected, and clinicopathological records were retrospectively reviewed and analyzed. Immunohistochemistry (IHC) for proliferative markers (Ki-67, PHH3) and STAT6 were performed.

Results: A total of 140 cases were collected, with mean follow-up of 77 months (median 58.8 months; range 0.53-540.5 months). 1-, 5-, 10-, and 20-year survival rates were 99.1, 94.0, 74.4, and 61.9 %, respectively. Thirty-nine patients (27.9 %) had recurrent disease. Mean and median times to recurrence were 62.9 and 47.3 months with 1-, 5-, 10-, and 20-year recurrence-free survival rates of 98.3, 78.3, 50.1, and 11.0 %, respectively. Thirteen patients (9.3 %) developed extracranial metastases. No adjuvant radiation therapy, higher histologic grades, failure of gross-total resection, and cases with gamma-knife surgery (GKS) were factors associated with shorter disease-free survival (log-rank test, p = 0.02, 0.00, 0.02, 0.00), among which high histologic grade and cases with GKS were significant in multivariable analysis. Strong nuclear STAT6 expression was noted in HPCs in 62 cases of HPCs (60/62, 96.8 %), whereas diffuse weak positivity was demonstrated in all meningioma cases.

Conclusions: The survival rate in patients with HPC of the CNS is comparable to that of previously reported series. Recurrence remains a critical clinical issue of the disease. Identification of NAB2-STAT6 fusion transcript with surrogate IHC marker is a valuable diagnostic tool in the differential diagnosis of the disease.