Anaplastic glioneuronal tumor with KIAA1549/BRAF fusion

: Glioneuronal tumors are usually low-grade and have favorable prognosis. The anaplastic glioneuronal tumor with KIAA1549/BRAF fusion has not yet been documented. This article reports a case of glioneuronal tumor with anaplasia and KIAA1549/BRAF fusion to illuminate the importance of KIAA1549/BRAF fusion in high-grade glioneuronal tumors. A ten-year-old boy presented with one year of headache and three months of blurry vision and proptosis. Ophthalmologic evaluation revealed bilateral papilledema. Magnetic resonance imaging showed a large mixed cystic and solid mass in the left frontal lobe of cerebrum. Histologic analysis demonstrated a neoplasm with pseudopapillary growth pattern, focal necrosis, microcalcification, and brisk mitotic activity with a high Ki67 labeling index of focally up to 20%. Immunohistochemical assessment identified a mixed glial and neuronal neoplastic cell population. Molecular studies revealed a KIAA1549/BRAF fusion. The histological and molecular changes are consistent with an anaplastic glioneuronal tumor with KIAA1549/BRAF fusion. In view of the fact that the effective, targeted therapies for the tumors with KIAA1549/BRAF fusion are available, detection of KIAA1549/BRAF fusion for high-grade glioneuronal tumors is clinically helpful.