Postoperative Development of Desmoid Tumor After Surgical Correction of Adult Spinal Deformity: Case Report and Review of Literature.

Background: Desmoid tumors are known to be rare and relatively slow growing with locally invasive histology and high recurrence rates. A rare subset of these tumors occurs adjacent to the spinal column after surgery. Since 1961, only 6 cases of postoperative paraspinal desmoid tumor have been reported. This report is the first to describe the occurrence of a paraspinal desmoid tumor after surgical correction of a spinal deformity.

Methods: A 56-year-old woman with multiple sclerosis reported 2-3 years of progressively worsening mid and low back pain that was worse with standing and ambulation and almost completely relieved with lying flat. Standing anteroposterior scoliosis radiographs revealed a thoracolumbar spinal deformity, which was surgically corrected with a T4 pelvis spinal fixation and fusion. At her 2-year postoperative clinic visit the patient reported good improvement in her preoperative symptoms but felt a fullness in her right upper back and neck that was nontender. Magnetic resonance imaging revealed a large tumor in this region. The tumor was resected en bloc, and pathology noted a 14.5 cm × 8.7 cm × 4.2 cm mass with spindle cell proliferation and positive staining for β-catenin (mutated gene found in 85% of desmoid tumors).

Conclusions: This is the first report of a postoperative desmoid tumor after spinal deformity correction and the seventh reported case in the spine literature. All reported cases have been women aged 39-57 years. The patient will be followed closely with magnetic resonance imaging given the known high local recurrence rate of this tumor.