LAUSR

BACKGROUND Incidentally discovered diffusely infiltrating low-grade gliomas (iDLGGs) are rare findings on neuroimaging that pose a challenge to neurosurgeons. There is a paucity of data regarding the natural history of these lesions and thus management is controversial. We characterize the growth rates and patterns of iDLGGs in a cohort of patients who underwent serial magnetic resonance imaging (MRI) prior to surgical treatment. METHODS We performed a retrospective review of all adult patients (>18years) diagnosed with diffusely infiltrating low-grade glioma between April 2004 and April 2016 at our institution. iDLGG was defined as any lesion discovered on computed tomography (CT) or MRI performed for reasons and/or symptoms not attributable to the lesion and confirmed on histopathology as a low-grade glioma. Tumor growth rates and patterns of growth were analyzed in patients who had serial imaging available. RESULTS Fifteen patients met the inclusion criteria. Mean velocity of diametric expansion (VDE) was 2.93 mm/year. 11 patients (73.3%) had tumors with an exponential growth pattern and the other 4 patients (26.7%) had a linear growth pattern. Initial tumor volume was positively correlated (r=0.78) with velocity of diametric expansion (VDE). CONCLUSION iDLGGs grow over time and the majority exhibit an exponential pattern of growth. Tumor volume at the time of diagnosis is predictive of a faster growth rate but not the pattern of growth.