Aggressive postoperative lumbar fibromatosis after the placement of instrumentation for treatment of spondylolisthesis. Case report.

This 50-year-old woman presented with a paravertebral lumbar fibromatosis (desmoid tumor) after undergoing the placement of instrumentation for lumbar spondylolisthesis. The tumor developed just cranial to the previous skin incision. Fibromatoses, or desmoid tumors, are uncommon infiltrative lesions that affect musculoaponeurotic structures, most often of the trunk and limbs. They are known to occur in association with surgery-related scars or implants and only rare examples appear in the neurosurgical and spine-related literature. In cases involving well-defined tumors in which radical resection is possible, surgery is the treatment of choice; however, the recurrence rate is high. The patient in the present case was followed for 14 months postoperatively and did not undergo radiotherapy; there was no recurrence. Although rare, this distinctive tumor should be considered in the differential diagnosis of postoperative paravertebral bulgings after neurosurgical and spinal operations.