Growth behavior of plexiform neurofibromas after surgery.

PURPOSE: The aim of this study was to analyze growth rate and identify prognostic factors for progression of postoperative plexiform neurofibromas in patients with neurofibromatosis type 1.

METHODS

We measured postoperative tumor volume change per year on magnetic resonance imaging. Linear regression models were applied to identify risk factors for tumor progression.

RESULTS

Fifty-two patients (mean age: 25.4 years (3.2-64.2 years)) with 56 plexiform neurofibromas were analyzed. Initial median tumor volume was 40.3 ml (SD: 1,552 (0-10,800)). Surgical indications included disfigurement (n = 21), pain (n = 20), and functional deficits (n = 16). Sixteen percent of all cases experienced acute surgical complication, and 13% showed late complication. Eight patients (19%; 6 children and 2 adults) with residual tumor had repeat surgery for tumor progression. Median tumor progression was 0.6% change per year (SD ± 27.4; range: -59.2 to 88.1) and 2.9% from baseline (SD ± 163.9; range -1,001.3 to 81.8). Patients aged 21 years and younger had the highest progression rate (P < 0.01). For every year of age, the mean growth rate decreased by -0.463 mean percent (P = 0.03). With age as a continuous variable, age, the site of the tumor, and depth were the only factors associated with tumor progression. Fourteen plexiform neurofibromas (10 nodular and 4 diffuse) in 13 patients (5 children and 8 adults) were completely resected (by visualization) and did not relapse during observation (mean: 2.9 years; range: 1.1-5.8 years).

CONCLUSION

Age, tumor type, location, and depth are helpful to estimate the progression of plexiform neurofibromas after surgery. Patients benefit from elective surgery of small and completely removable plexiform neurofibromas.