Growth curves of renal masses from patients with von Hippel-Lindau disease

Purpose: To analyse the progression curves of renal masses (RMs) in patients with von Hippel-Lindau disease (VHL), and propose some changes in their management. Methods and Materials: This retrospective study included 26 VHL patients who underwent periodical magnetic resonance imaging (MRI) examinations as follow-up for renal masses. Thirty-one of total 60 RMs (51.7%) were classified as solid tumours (STs), and remaining 29 of 60 (48.3%) as complex cysts (CCs). For each lesion, the volume was estimated at each MRI occurrence using the ellipsoid approximation, and individual growth curves were traced. Variations in volume over time were analysed, and the mean growth rates (MGRs) calculated. MGRs were used to compare STs and CCs. Results: In cases for which several imaging occurrences were available, the analysis of growth curves showed that solid tumours had an initial fast growth, followed by slower growth, according to the Gompertzian model. Otherwise, complex cysts showed some fluctuating progression curves, with spontaneous regressions in volume. Medians of the MGRs were 1.28 cm3/y for STs and 0.37 cm3/y for CCs, respectively, leading to statistically significant difference (P=0.0023), and indicating a growing process substantially slower for CCs than for STs. Conclusion: This study showed that short-term MRI follow-up and multiple lesion volume measurements in VHL patients, would allow a more accurate estimation of the tumour growth curve, providing useful information to possibly postpone the lesion treatment. Less aggressive approach seems to be possible for complex cysts versus solid tumours.