Evidence for the genesis of WHO grade II glioma in an asymptomatic young adult using repeated MRIs.

As the natural course of WHO grade II glioma (G2G) during their initial silent period is unknown, the G2G genesis and their "date of birth" are a matter of debate. Here, a left temporo-insular G2G was discovered incidentally in a 31-year-old man in 2009 (MRI performed for a Chiari malformation). The mean tumor diameter increased from 29 (April 2009) to 31 mm (October 2009) before surgery. Since we recently demonstrated that the growth rate is constant during the initial silent period in G2G, the extrapolation backward in time leads to date the glioma birth in 2002. This observation is in agreement with an MRI performed in 1997, where no signal abnormality was detected. To our knowledge, this is the first report demonstrating that the tumorigenesis of a G2G occurs during the young adult period. In addition, estimation of the date of birth may serve as a reproducible "starting point" when analyzing survivals in series of G2G.