Clinical and Molecular Characteristics, Management and Outcome of Infantile Fibrosarcoma: A Retrospective 18-Year Single-Institution Review

Abstract

Infantile fibrosarcoma (IFS) is the most common non-rhabdomyosarcoma soft-tissue sarcoma in children under 1 year of age, with local aggressiveness, but a high cure rate with conservative treatment. We report our experience with 15 patients with histological diagnosis of IFS treated at our Institution from January-2003 to December-2020. The median age was 6.72 months (range: 0-36); 66% were males. The extremities were the most common tumor site (66.7%). The tumor size was > 5 cm in 10 patients. Only one patient had metastatic disease (lung). Molecular studies were performed in 14 patients and were positive in ten: nine ETV6/NTRK3 and one RAF1. Initial non-mutilating surgery was performed in six patients. A delayed surgery could be performed in 4/8 patients after neoadjuvant chemotherapy with Vincristine - Actinomycin-D, and in one patient a watch-and-wait strategy was adopted. With a median follow-up of 58.67 months, all patients are alive except for the patient with metastatic disease. The 5-year overall and event-free survival were 93.5% and 86.5% respectively. Although IFS is locally aggressive, it has a high rate of overall survival due to its good response to chemotherapy and non-mutilating surgery even with involved margins. Advances in molecular genetics have improved diagnosis and refined classification.