Evaluation of KIAA1549::BRAF fusions and clinicopathological insights of pilocytic astrocytomas

Iman Dandapath; Sumanta Das; Bheru Dan Charan; Ajay Garg; Ashish Suri; Shweta Kedia; Mehar Chand Sharma; Chitra Sarkar; Yookarin Khonglah; Shabnam Ahmed; Vaishali Suri

doi:10.1016/j.anndiagpath.2024.152318

Evaluation of KIAA1549::BRAF fusions and clinicopathological insights of pilocytic astrocytomas

Ann Diagn Pathol. 2024 Apr 23:72:152318. doi: 10.1016/j.anndiagpath.2024.152318. Online ahead of print.

Authors

Affiliations

¹ Neuropathology Laboratory, Neurosciences Centre, All India Institute of Medical Sciences, New Delhi, India.
² Department of Neuroradiology, All, India Institute of Medical Science, New Delhi, India.
³ Department of Neurosurgery, All India Institute of Medical Sciences, New Delhi, India.
⁴ Department of Pathology, All India Institute of Medical Sciences, New Delhi, India.
⁵ Department of Pathology, North Eastern Indira Gandhi Regional Institute of Health and Medical Sciences, Shillong, Meghalaya, India.
⁶ Department of Pathology, GNRC Hospitals, Dispur, Assam, India.
⁷ Neuropathology Laboratory, Neurosciences Centre, All India Institute of Medical Sciences, New Delhi, India. Electronic address: surivaishali@yahoo.co.in.

PMID: 38733671
DOI: 10.1016/j.anndiagpath.2024.152318

Abstract

Background: Pilocytic astrocytoma (PAs) represents a significant portion of childhood primary brain tumors, with distinct histological and radiological features. The prevalence of KIAA1549::BRAF fusion in PAs has been well-established, this study aims to assess the prevalence of KIAA1549::BRAF fusions and explore their associations with tumor characteristics, radiological findings, and patient outcomes in PAs.

Methods: Histologically confirmed cases of PAs from a 5-year period were included in the study. Demographic, histopathological, and radiological data were collected, and immunohistochemistry was performed to characterize tumor markers. FISH and qRT-PCR assays were employed to detect KIAA1549::BRAF fusions. Statistical analyses were conducted to examine associations between fusion status and various other parameters.

Results: Histological analysis revealed no significant differences in tumor features based on fusion status. However, younger age groups showed higher fusion prevalence. Radiologically, fusion-positive cases were distributed across different tumor subtypes SE, CWE and NCWE. Survival analysis did not demonstrate a significant impact of fusion status on overall survival, however most cases with recurrence and death harboured KIAA1549::BRAF fusion. Of 200 PAs, KIAA1549::BRAF fusions were detected in 64 % and 74 % of cases via qRT-PCR and FISH, respectively. Concordance between the two platforms was substantial (86 %).

Conclusion: KIAA1549::BRAF fusions are prevalent in PAs and can be reliably detected using both FISH and qRT-PCR assays. Cost considerations suggest qRT-PCR as a more economical option for fusion detection in routine clinical practice.

Keywords: FISH; Fusions; KIAA1549::BRAF; Pilocytic Astrocytoma; qRT-PCR.