Introduction: Molecular and genetic information have become critical cornerstones in brain tumor diagnosis and treatment. Studies have shown that approximately 90% of papillary craniopharyngioma contain BRAF V600E mutations. A phase II trial of BRAF V600E+ papillary craniopharyngioma treated with BRAF/MEK inhibitors showed 94% response rate and 91% tumor volume reduction. During resection of craniopharyngioma, disruption of the pituitary/hypothalamic axis is often inevitable, requiring hormone replacement. Determination of tumor genotype prior to surgical resection can alter the available treatments. Despite interest in developing “liquid-biopsies” for noninvasive preoperative detection and diagnosis of CNS tumors, results thus far have been unsuccessful.
We present two cases of patients with craniopharyngiomas that underwent standard endoscopic endonasal approaches. Upon visualizing the tumor, biopsy was performed using cup forceps and sent for permanent pathology and an ultra-rapid BRAF V600E PCR analysis. In approximately 15 minutes the PCR resulted, providing real-time information regarding the mutational status of the tumor.
Methods: Bead homogenization in the presence of a detergent-free DNA extraction buffer was used to lyse the cells from the tissue sample. DNA was isolated from associated proteins and cellular debris. An ultra-rapid ddPCR based assay determined the mutational status intraoperatively. Histopathological analysis (H&E and immunohistochemistry) was performed on permanent pathology specimen.
Results: In one case, the tumor was found to harbor BRAF V600E mutation, so the decision was made to close without resecting further tumor and proceed with combination BRAF-MEK inhibitor therapy. The other tumor was negative for the mutation, consistent with an adamantinomatous craniopharyngioma, so gross total resection was pursued. PCR findings were corroborated by standard immunohistochemical analysis.
Conclusion : Through use of an intraoperative ultra-rapid PCR, we can rapidly determine BRAF V600E mutational status, which directly impacts our clinical decision in real-time. This presents an innovative approach for intraoperative diagnosis and characterization of craniopharyngioma, with profound treatment implications.
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