Intracranial Solitary Fibrous Tumors With Glandular and Papillary Structures: A Case Report.

Solitary fibrous tumor (SFT) is a fibroblastic neoplasm with NAB2 and STAT6 gene fusion as well as STAT6 nuclear expression. Uncommon variants of intracranial SFTs, such as glandular and papillary structures, are extremely rare. We present a rare SFT case in a 64-year-old female demonstrating unprecedented glandular structures and extensive myxoid stromal changes. This morphologic divergence underscores the imperative for molecular validation in SFTs with atypical histologic features. Our findings advocate a refined diagnostic protocol: RNA-based next-generation sequencing (RNA-NGS) must be prioritized in STAT6-immunopositive central nervous system (CNS) mesenchymal tumors when DNA-NGS fails to identify the pathognomonic NAB2::STAT6 fusion, as demonstrated by the resolution of diagnostic ambiguity through detection of a cryptic NAB2-exon4::STAT6-UTR fusion in this case.