Purpose: To determine whether the type of VHL gene pathogenic variant influences the growth rate or CT enhancement values of renal lesions in VHL patients.
Materials and methods: Thirty-two VHL patients (19 male) were selected from a prospectively maintained imaging database for patients that underwent surgical tumor resection between 2014 and 2016. One hundred and eleven VHL lesions were marked for resection and pathology analysis. Whole lesion volumetric segmentation was performed on nephrographic phase of the two most recent contrast-enhanced CT scans before surgery. Intensity distribution curves were obtained from segmentations. A linear mixed model, accounting for within-patient correlations, was used to compare the growth and enhancement differences between different germline pathogenic variant types.
Results: There was no significant difference for the lesions' total growth between different germline pathogenic variants (P value = 0.78). The median growth rate for all lesions was 1.7 cc/year (IQR 0.5, 3.9) with a baseline median size of 4.1 cm3 (IQR 1.7, 11.7). In complex lesions, the solid portion of the tumor demonstrated a higher growth rate (1.6 cc/year) than cystic portions (0.02 cc/year) which stayed relatively unchanged. Only one pathogenic variant (Splice donor) showed some levels of difference in its relative enhancement from other subtypes.
Conclusion: The type of germline pathogenic variant on the VHL gene does not affect the growth rate or CT enhancement values of renal lesions in patients with VHL. The absolute growth rate of these tumors may be used in the scheduling of follow-up studies.
Keywords: Computed tomography (CT); Growth rate; Pathogenic variant; Volumetric analysis; von Hippel-Lindau.