Langerhans cell histiocytosis (LCH) is a clonal malignancy of dendritic cells. Treatment options considered included radiotherapy of the pituitary gland, chemotherapy, and targeted therapy on the basis of the molecular finding. Positron emission tomography-computed tomography and MRI performed in week 12 of treatment showed a slight increase of the pituitary gland in size; however, the patient had not been receiving trametinib in the previous 3 weeks. Treatment was well tolerated, with manageable cutaneous toxicity, a common adverse event related to trametinib.[13] Besides an objective response, the patient reported an improved quality of life, suggesting MEK inhibition as a promising therapeutic approach in patients with LCH with mutated I MEK1 i (p.E102 I103delEI). [Extracted from the article]