Predictive factors with the growth of remnant tumor after incomplete resection of thoracic dumbbell-shaped schwannomas.

STUDY

DESIGN

Retrospective cohort study.

OBJECTIVES

Thoracic dumbbell-shaped schwannomas (DS) often require incomplete resection (IR) because of anatomical constraints. This study aimed to compare outcomes between gross total resection (GTR) and IR and to identify factors associated with postoperative regrowth of remnant tumors after IR.

SETTING

Single academic institution.

METHODS

Patients with thoracic DS surgically treated between 2002 and 2021 were retrospectively reviewed. All patients underwent at least two postoperative MRI examinations and were followed for a minimum of 2 years. Patients were classified into GTR and IR groups; IR cases were further divided according to the presence or absence of postoperative tumor regrowth (>2 mm). Clinical variables, surgical factors, remnant margin zone, residual tumor volume, and regrowth direction were analyzed. Residual tumor volume was measured using three-dimensional volumetric analysis.

RESULTS

Thirty-eight patients were included (24 GTR, 14 IR). Postoperative improvement in visual analog scale scores was significantly greater in the GTR group. Among IR cases, 7 patients showed postoperative tumor regrowth. No significant differences were observed between regrowth and non-regrowth groups in age, Eden classification, surgical approach, or remnant margin zone. Residual tumor volume was significantly larger in cases with regrowth (p = 0.016). Tumor regrowth predominantly occurred in the extraforaminal direction.

CONCLUSIONS

In thoracic DS, larger residual tumor volume is associated with postoperative regrowth, possibly reflecting complex segmental vascular anatomy. When safely feasible, GTR remains the preferred strategy to minimize the risk of remnant tumor regrowth.