Introduction Neurofibroma type 1 (NF1) is a rare genetic disease with onset in early childhood. Plexiform neurofibromas (PN), benign tumors along the nerves, are a common and chronic complication of NF1 occurring in 20% to 50% of NF1 patients (Nguyen et al., 2011; Tchernev et al., 2016; Miller et al., 2019). PN can be painful, potentially life-threatening, and often cannot be surgically removed, depending on the size and proximity to vital tissues. The aim of this study was to describe treatment patterns and healthcare resource utilization in pediatric NF1 patients with symptomatic inoperable PN in the US prior to US FDA approval of selumetinib. Methods This was a retrospective chart review of pediatric NF1 patients with symptomatic inoperable PN from 3 NF1 treatment centers in the US. Patient records were abstracted if the patient (1) received NF1 diagnosis from 1.Jan.2000 to 31.Dec.2018, (2) was 2 to 18 years old at the time of diagnosis, (3) was diagnosed with ≥1 symptomatic inoperable PN, (4) received care on-site for ≥12 months, and (5) had ≥3 site visits prior to the end of the study period on 31 Dec 2019. Records were abstracted at the patient’s first, last, and “midpoint” visits (the visit nearest the midpoint between the first and the last). Results There were 102 pediatric patients with at least one symptomatic inoperable PN, of which 84 (82.4%) received treatment for their PN. Most patients were male (n=66, 64.7%) and the median age at diagnosis of first symptomatic inoperable PN was 6 years. On average, patients received 3.4 monitoring/imaging scans per year with MRI (2.0 per patient per year [PPPY])]) and x-rays (1.3 PPPY) being the most common. Patients attended 6.1 outpatient visits per year, on average, with 0.3 emergency room visits PPPY. Nearly half (n=50, 49.0%) were hospitalized at least once for an average rate of 0.2 hospitalizations PPPY. Among those who received treatment, 53 (63.1%) received pharmacotherapy. The most common pharmacotherapies were gabapentin (n=16, 30.2%) and NSAIDs (n=7, 13.2%) for pain, and selumetinib (n=13, 24.5%) and trametinib (n=9, 17.0%) for PN shrinkage.. Chemotherapy was used to treat PN in 6 (5.9%) patients, half of which had PN progression despite treatment. Conclusions There is a substantial burden of monitoring and treatment of NF1 PN on patients and the healthcare system. Access to effective long-term pharmacological treatment to control PN progression may reduce the healthcare burden on patients and the healthcare system. Miller DT, Freedenberg D, Schorry E, Ullrich NJ, Viskochil D, Korf BR; Council on Genetics and American College of Medical Genetics and Genomics. Health supervision for children with neurofibromatosis type 1. Pediatrics. 2019;143(5). Nguyen R, Kluwe L, Fuensterer C, Kentsch M, Friedrich RE, Mautner VF. Plexiform neurofibromas in children with neurofibromatosis type 1: frequency and associated clinical deficits. J Pediatr. 2011; 159(4):652-5.e2. Tchernev G, Chokoeva AA, Patterson JW, Bakardzhiev I, Wollina U, Tana C. Plexiform neurofibroma: a case report. Medicine (Baltimore). 2016 Feb;95(6):e2663.