Identifying Lesions of the Corpus Callosum in Patients with Neurofibromatosis Type 1

Purpose To investigate the rate of lesions of the corpus callosum (CC), specifically unidentified bright objects (UBOs) and gliomas, in a large cohort of Neurofibromatosis type 1 (NF1) patients. Methods We reviewed the medical records of 681 patients (aged 3 months to 86 years) followed at our institution from 2000-2023 with a diagnosis of NF1 and ≥ 1 brain MRI. Patients with UBOs or gliomas in the CC were identified and the change in lesions over time was recorded. RAPNO/RANO criteria were used to determine changes in size. Results Forty-seven patients had CC UBOs (9.2% of the 512 patients with any UBO). The majority of CC UBOs were in the splenium (66.0%), followed by the body (21.3%), and genu (12.8%). Seventeen patients had CC gliomas, two of whom had 2 gliomas, representing 10% of the 170 patients with any glioma. Seventeen of nineteen gliomas were in the splenium. Over follow-up, 8/19 remained stable, 3/19 decreased in size, and 8/19 increased in size. The mean percentage change in the product of the dimensions was 311.5% (ranging from -46.7% to 2566.6%). Of the 8 lesions that grew, only one required treatment. Conclusions There is a 6.9% and 2.5% prevalence of CC UBOs and gliomas, respectively, in our cohort of patients with NF1. Most lesions are present in the splenium, and while some gliomas demonstrate significant growth, they rarely require treatment. This work is the largest series of corpus callosal lesions in NF1 and adds to growing data to better inform appropriate follow-up.