RT Journal Article SR Electronic T1 FIP1L1–PDGFRA positive chronic eosinophilic leukaemia and associated central nervous system involvement JF Journal of Clinical Pathology JO J Clin Pathol FD BMJ Publishing Group Ltd and Association of Clinical Pathologists SP 677 OP 680 DO 10.1136/jcp.2007.052100 VO 61 IS 5 A1 C Williams A1 S Kalra A1 U Nath A1 N Bown A1 V Wilson A1 B S Wilkins A1 A J Neylon YR 2008 UL http://jcp.bmj.com/content/61/5/677.abstract AB Interstitial deletion involving chromosome 4q12 generates the novel tyrosine kinase fusion protein encoded by FIP1L1–PDGFRA, which is present in many patients previously labelled as having hypereosinophilic syndrome, initially reported in 2003. Reports in recent literature document excellent clinical and molecular response to the tyrosine kinase inhibitor imatinib (Glivec). This report describes the case of a 58-year-old lady, diagnosed with FIP1L1–PDGFRA positive hypereosinophilic disorder, who subsequently developed symptoms related to an intracranial lesion. Biopsy and molecular genetic studies confirmed a diffuse infiltrative lesion, with evidence of FIP1L1–PDGFRA gene fusion. Initiation of imatinib treatment led to impressive clinical and radiological response.