Measuring growth of residual cholesteatoma in subtotal petrosectomy

Background: Little is known about the growth rate of cholesteatoma in patients.Objective: Investigate the growth of residual cholesteatoma in subtotal petrosectomy based on volume measured in MRI scans.Materials and methods: Retrospective case series in a Tertiary Medical Centre. Thirteen residual cholesteatomas were identified in 10 patients after subtotal petrosectomy for which a wait-and-scan policy was adopted. Volume of the residual cholesteatoma was calculated by manual segmentation as well as the ‘box method’.Results: Mean growth rate was 27.9 mm3/month (SD 22.8), with a large individual variation ranging from 2.2 to 69.8 mm3/month. No complications were reported in 10 patients with a wait-and-scan policy for residual cholesteatoma in subtotal petrosectomy. The box method overestimates growth rate compared to the reference method manual segmentation and a linear increase of this systematic error was seen with increasing size of the cholesteatoma.Conclusions: Residual cholesteatoma growth rate shows a large individual variation. A wait-and-scan policy could be considered in case of a (small) residual in subtotal petrosectomy with ample room to grow before destroying any remaining structures. Furthermore, the clinically more applicable and less time-consuming box method can be used to accurately measure volumes of small cholesteatomasup to a volume of 500 mm3.