Desmoid-type fibromatosis in children. Clinical features, treatment response, and long-term follow-up

Desmoid-type fibromatosis (DF) is a tumor with high local recurrence rate. Sixteen patients (18 desmoid tumors) were retrospectively evaluated. Initial surgery was performed in 13/18 tumors, with complete resection in 6 (one with free margin and five with microscopic residual disease); 10/13 had local relapse. Eleven patients with 13 tumors underwent treatment with methotrexate-vinblastine. The response rate to chemotherapy was 54%, and up to 81% if stable disease cases were included. The best response was partial remission. Only 2 had grade 4 toxicity. Twelve of 15 patients had sequelae. In 8 cases sequelae were directly related to the surgical intervention and 3 of them were severe. The 5-year progression-free survival and overall survival were 30% and 93.3%, respectively. DF has a high local relapse rate, regardless of surgical margin involvement. Low dose chemotherapy achieved stable disease and even remission of the lesions with low toxicity. The high rate of sequelae is probably related to the initial surgery performed in the majority of patients and may be avoided by the use of neoadjuvant low dose chemotherapy.