P18 Giant Periocular Juvenile Xanthogranulomas Treated with Trametinib

Abstract

Abstract Juvenile Xanthogranuloma (JXG), the commonest type of non-Langerhans cell histiocytosis, is regarded as a benign self-limiting condition of infancy, characterised by asymptomatic yellow brown papulonodular lesions, usually confined to the skin but occasionally affecting the eyes or internal organs. Skin lesions characteristically regress spontaneously within 3-6 years. We describe an unusually aggressive cutaneous presentation requiring input from paediatric oncology. A 6 year old boy presented with extensive soft yellowish papules, plaques and nodules particularly around the eyes but also over the chest and leg. Biopsy confirmed the clinical diagnosis of JXG. The lesions enlarged progressively with new lesions appearing, causing significant distortion of the upper and lower eyelids with reduced ability to open the eyes, discomfort and distress. Treatment was started with topical steroids, progressing to intralesional and systemic steroids, but with minimal effect. In view of the severity, vinblastine and subsequently cytarabine were added, again with limited benefit. The periocular lesions were surgically debulked and he was commenced on Trametinib (a MEK inhibitor) with a good response. Now aged 9 years, and the patient displayed a favourable clinical response after 3 months of being on Trametinib. JXG rarely requires treatment, but there is no recognised therapy for the occasional problematic lesions. In this case trametinib was effective and well-tolerated. The efficacy of trametinib in histiocytosis has been attributed to the presence of activating BRAF and MAP2K1 mutations. Genetic analysis of JXG may guide future therapies.