Differential Diagnosis of Meningeal SFT HPC and Meningioma: Which Immunohistochemical Markers Should Be Used?
Meningeal solitary fibrous tumors hemangiopericytomas (SFT HPC) and meningiomas can be difficult to distinguish on histologic examination. STAT6 immunohistochemistry (IHC) is a reliable diagnostic marker of SFT HPCs. Recently, GRIA2 has also been reported to be a diagnostic marker of SFT HPC, although no extensive data are available for meningeal SFT HPCs yet. The aim of this study was to test their diagnostic performance in a large cohort of SFT HPCs and meningiomas. IHC analyses for GRIA2 and STAT6 were performed on tissue microarrays containing 76 SFT HPCs and 181 meningiomas. Results were compared with previous data with ALDH1 and CD34. Two different anti STAT6 antibodies were tested: SC 20 polyclonal and YE361 monoclonal antibody. Ninety six percent of meningeal SFT HPCs but no meningioma displayed nuclear STAT6 positivity. With SC 20 antibody, concomitant cytoplasmic staining for STAT6 was observed in >50% of all cases, including meningiomas. However, using YE361 antibody, cytoplasmic staining was absent, and nuclear signal intensity was stronger leading to better interpretation of STAT6 IHC. GRIA2 was positive in 84% of SFT HPCs and in 16% of meningiomas. STAT6 had excellent sensitivity (96% and specificity (100% ALDH1 and GRIA2 had same sensitivity (84% but ALDH1 and CD34 had better specificity than GRIA2 (97% and 96% vs. 84% respectively) For the differential diagnosis of SFT HPCs versus meningiomas, the best diagnostic approach is to perform STAT6, followed by ALDH1 and CD34 in the case of uncommon STAT6 negative cases. Because of meningioma positivity, GRIA2 seems less useful in this indication.
The American journal of surgical pathology