A novel KIF5B-ALK fusion in a child with an atypical central nervous system inflammatory myofibroblastic tumour

An 11-year-old girl presented with global developmental delay. As part of her routine work-up for her developmental disability, MRI of the brain was performed and demonstrated a contrast-enhancing lesion with reduced diffusivity in the right parietal lobe (figure 1). A stereotactic robotic-assisted needle biopsy revealed microglial proliferation and lymphocytic inflammation, indicating potential microglioma or gliofibroma; however, a more definitive diagnosis was not established given the limited tissue. Early repeat MRI showed areas of progression, and gross total resection was performed. The pathology demonstrated a moderately cellular proliferation of spindle cells with scattered mitotic figures, and a mixed inflammatory infiltrate of scattered lymphocytes, plasma cells and eosinophils (figure 2A). The areas of nodular spindle cell proliferation were diffusely immunopositive for CD68 and negative for CD30, …