Extra-abdominal aggressive fibromatosis (EAAF) is a benign desmoid tumor with potentially aggressive behavior. Surgical treatment has a very high rate of recurrence, sometimes with significant morbidity. We conducted a prospective clinical and MRI surveillance study of our patients (clinical and MRI) with EAAF to search for prognostic factors.

This cohort included 17 patients with EAAF. For nine patients, biopsy alone was performed. For eight, the tumor was a recurrence after surgical removal. Patients were seen for a clinical assessment and MRI every 6 months.

Median follow-up was 42 months (range, 6-114). Three patients worsened clinically with pain or functional impairment. One patient required neurosurgery to control pain (good, stable outcome). MRI showed progression for two tumors (12%), in one case despite drug treatment, although follow-up has been short since diagnosis (9 and 14 months). Three tumors regressed and 12 remained stable on successive MRIs. On average, the tumor growth evolved over 10 months.

Tumor growth was never noted beyond 36 months. This notion of an interruption in tumor growth is mentioned sporadically in reports on EAAF, which have generally included recurrent tumors. To our knowledge, this is the first series reporting tumors left in place followed up with modern imaging techniques. The high rate of spontaneous interruption of tumor growth must be counterbalanced with the difficult task of local treatment: the risk of recurrence is particularly high after surgery and functional sequelae can be significant when wide resection is proposed in an anatomically difficult location. The precise role for surgery, and whether it should be combined with radiotherapy, remain to be determined. There are only a few reports on general treatments. With this information in mind, we propose that surgical resection should not be considered the only solution for the treatment of EAAF. Further work is needed to define the useful contribution of simple surveillance of these benign tumors.