Prognostic significance of NAB2–STAT6 fusion variants and TERT promotor mutations in solitary fibrous tumors/hemangiopericytomas of the CNS: not (yet) clear

Excerpt

Grading of meningeal solitary fibrous tumors/hemangiopericytomas (SFTs/HPCs) of the central nervous system (CNS) is nowadays based on histologic criteria as described in the revised fourth edition of the WHO Classification of CNS tumors [10] or the more recently published, updated version of the Marseille Grading System (MGS) [11]. Histology-based grading of CNS SFTs/HPCs allows for discriminating subgroups with significant differences in prognosis. However, the often piece meal resection of these tumors may hamper adequate evaluation of mitotic activity and necrosis, and thereby assessment of malignancy grade. NAB2–STAT6 fusion is the molecular hallmark of both soft tissue SFTs and CNS SFTs/HPCs, and the resulting fusion protein accumulates in the nucleus and acts as a transcriptional activator of early growth response mediated pathways with STAT6 immunohistochemistry being a very sensitive and specific tool for their diagnosis [5, 8, 12, 14]. For soft tissue SFTs, particular NAB2–STAT6 fusion variants as well as telomerase reverse transcriptase (TERT) promoter mutations leading to telomerase activity and tumor cell immortalization have been reported to have prognostic value. Some studies have included CNS SFTs/HPCs in their cohort, but because of small numbers and lack of (long term) follow-up data the prognostic value of these markers for CNS SFTs/HPCs is still unclear [1‐4, 6, 7, 9, 13, 15, 16]. …