Retrospective Cohort Analysis of the Impact of Puberty on Plexiform Neurofibroma Growth in Patients with Neurofibromatosis Type 1

Abstract

To assess the hypothesis that plexiform neurofibroma (PN) growth rates increase during puberty. PN growth rates before and during puberty were compared in a retrospective cohort of children with neurofibromatosis type 1 with puberty defined by Tanner staging. Of 33 potentially eligible patients, 25 had adequate quality magnetic resonance imaging for volumetric analysis and were included in ≥1 anchor cohort. Volumetric analysis was performed for all available imaging studies within the 4years before and after puberty, and before and after 9- and 11-year-old anchor scans. Linear regression was performed to estimate the slope of change (PN growth rate); growth rates were compared with paired t test or Wilcoxon matched-pairs signed rank test. There were no significant difference in rates of PN growth in milliliters per month or milliliters per kilogram per month in the prepubertal vs pubertal periods (mean,1.33±1.67 vs 1.15±1.38 [P=.139] and -0.003±0.015 vs -0.002±0.02 [P=.568]). Percent increases of PN volumes from baseline per month were significantly higher prepubertally (1.8% vs 0.84%; P=.041) and seemed to be related inversely to advancing age. Puberty and its associated hormonal changes do not seem to influence PN growth rate. These findings support those previously reported, but from a typical population of children with neurofibromatosis type 1 with puberty confirmed by Tanner staging.