Infantile Fibrosarcoma
Also written as: IFS
A low-grade malignant spindle-cell tumour of infancy and early childhood harbouring the ETV6–NTRK3 fusion, associated with a comparatively favourable prognosis relative to adult fibrosarcoma.
Full Definition
Infantile fibrosarcoma (IFS), also termed congenital fibrosarcoma when present at birth, is the most common soft-tissue sarcoma in children under one year of age. It is characterised by a herringbone or fascicular growth pattern of primitive spindle cells and is defined molecularly by the ETV6–NTRK3 gene fusion, which is also targetable by TRK inhibitors. Despite its histologically alarming appearance, IFS carries a markedly better prognosis than adult-type fibrosarcoma, with high rates of chemotherapy responsiveness and overall survival. Editors must note that 'congenital' and 'infantile' fibrosarcoma are used interchangeably in the literature; the WHO now groups this entity within 'NTRK-rearranged spindle cell neoplasm'.
Usage
Usage note: The WHO 2020 preferred term is 'NTRK-rearranged spindle cell neoplasm'; however, 'infantile fibrosarcoma' remains widely accepted and understood in clinical practice.
In Context
- "Molecular testing confirmed the ETV6–NTRK3 fusion, supporting a diagnosis of infantile fibrosarcoma in this three-month-old." — Molecular pathology report
- "Authors should note that 'infantile fibrosarcoma' and 'congenital fibrosarcoma' are synonymous; the former is preferred in current WHO nomenclature." — Journal editorial note