LETTER TO THE EDITORTITLE: Sarcoid-like reaction in a child following prolonged therapeutic exposure to dabrafenib and trametinib for BRAF V600E mutated hypothalamic/ chiasmatic gliomaAuthors : Mari Wilhelmsson MD, PhD1,2; Foo Jen Chun MD1; Rae S M Yeung MD, PhD3; Fiona Krtizinger MBChB, MMed4; Tata McKeown, MSc1; Ailish Coblentz, MD5; Birgit Ertl-Wagner, MD5; Uri Tabori MD, PhD1, Ute Bartels MD, PhD 1; Anirban Das MBBS, MD, DM 1AFFILIATIONS: 1. Division of Haematology Oncology, The Hospital for Sick Children, Toronto, Ontario, Canada; 2. Department of Women´s and Children´s Health, Karolinska Institutet, Stockholm, Sweden. 3. Division of Rheumatology, The Hospital for Sick Children, Toronto, Ontario, Canada. 4. Division of Respiratory Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada. 5. Department of Diagnostic Imaging, The Hospital for Sick Children, Toronto, Ontario, Canada.WORD COUNT:   853FIGURES:  1RUNNING TITLE: Sarcoid-like reaction with BRAF/MEK-inhibitionKEYWORDS : MEK-inhibitor, BRAF inhibitor, sarcoidosis/sarcoid‑like reaction (S/SLR), Low-grade glioma, pediatric

Targeted therapies are increasingly used in the management of pediatric low grade glioma. How-ever for patients who show resistance to these treatments, limited options are available. We pre-sent the case of a patient with BRAFV600 mutated low grade glioma who showed progression on a combination of trametinib and dabrafenib. Discontinuation of treatment was associated with a life-threatening deterioration and reintroduction of targeted therapy had no effect. The patient eventually showed a dramatic response to TPCV (thiguanine, procarbazine, CCNU and vincris-tine) , which suggests a role of chemotherapy in these situations.