A novel SREBF1::NACC1 gene fusion in an unclassifiable intracranial tumour.

A 39-year-old man had an intracranial tumour without infiltration into the surrounding cerebral tissue. The tumour recurred seven times in 11 years but maintained a well-demarcated character. Histopathological examination of the 4th surgical specimens showed nests of tumour cells surrounding small blood vessels. The tumour cells harboured amphophilic cytoplasm and small round nuclei with fine chromatin, and perinuclear haloes and clear borders were frequently observed, which was unclassifiable histology. By the Deutsches Krebsforschungszentrum methylation classifier, the tumour was not classified into any of the methylation classes. mRNA sequencing identified a novel SREBF1::NACC1 gene fusion. This intracranial tumour could be a novel tumour entity with NACC1 rearrangement showing characteristic histological and diagnostic imaging findings.