Spinal Solitary Fibrous Tumors: An Original Multicenter Series and Systematic Review of Presentation, Management, and Prognosis

SIMPLE SUMMARY: Solitary fibrous tumors are rare benign or cancerous tumors that develop in all tissues, including close to the spinal cord. These cases are exceptional and we describe their presentation and outcome based on 31 published cases and 10 patients on whom we operated. The tumors can develop in any portion of the spine and cause back pain, associated with neurological deficits, such as compression of a nerve or the spinal cord, in 66% of patients. Surgical removal is the first step towards diagnosis and treatment, but complete removal could be achieved in only 70% of patients, due to bleeding or spinal cord invasion. Tumors were found to recur after a mean 5.8 years (1 to 25), without identified risk factors. However, in patients with subtotal removal, radiotherapy significantly improves the rate of recurrence. In total, spinal solitary fibrous tumors are treated by neurosurgeons on the front line but discussion in a multidisciplinary team will provide general treatments, especially radiotherapy after subtotal removal. ABSTRACT: All solitary fibrous tumors (SFT), now histologically diagnosed by a positive nuclear STAT6 immunostaining, represent less than 2% of soft tissue sarcomas, with spinal SFT constituting a maximum of 2% of them, making these tumors extremely rare. We provide an up-to-date overview of their diagnosis, treatment, and prognosis. We included 10 primary STAT6-positive SFT from our retrospective cohort and 31 from a systematic review. Spinal pain was the most common symptom, in 69% of patients, and the only one in 34%, followed by spinal cord compression in 41%, radicular compression, including pain or deficit, in 36%, and urinary dysfunction specifically in 18%. Preoperative diagnosis was never obtained. Gross total resection was achieved in 71%, in the absence of spinal cord invasion or excessive bleeding. Histologically, they were 35% grade I, 25% grade II, and 40% grade III. Recurrence was observed in 43% after a mean 5.8 years (1 to 25). No significant risk factor was identified, but adjuvant radiotherapy improved the recurrence-free survival after subtotal resection. In conclusion, spinal SFT must be treated by neurosurgeons as part of a multidisciplinary team. Owing to their close relationship with the spinal cord, radiotherapy should be considered when gross total resection cannot be achieved, to lower the risk of recurrence.