Natural progression and tumor growth predictive factors of retroperitoneal schwannoma

Abstract

Background: It is important to know the natural history of retroperitoneal schwannoma including the growth rate in deciding the indication and timing of surgery in such nonpalpable tumors. However, the natural history of this tumor remains unclear. This study aimed to clarify the natural history and whether magnetic resonance imaging (MRI) findings and clinical findings can predict the future growth of this tumor.

Materials and Methods: Of patients with retroperitoneal schwannoma treated in our department from January 1, 2015, to December 31, 2015, eight patients who were followed up by MRI and without removal for more than 1 year were enrolled. Changes in lesion size were examined in relation to some clinical and MRI findings. In cases with pressure erosion in the vertebral body, a change in the size of the intraosseous part was compared to a change in the size of the whole lesion.

Results: The median absolute growth rate (AGR) was 1.9 cm³/year, the median relative growth rate (RGR) was 5.6%/year, and the median tumor volume doubling time (VDT) was 3.1 years. The AGR, RGR, and VDT were not related to any clinical findings. The intraosseous part showed RGR and VDT around twice that of the whole lesions.

Conclusions: The growth rates of retroperitoneal schwannomas were various. Additionally, MRI findings and clinical findings that could predict the future growth of retroperitoneal schwannoma could not be clarified. Therefore, careful follow-up is necessary for this tumor, especially for lesions with bone erosion.