Nodular fasciitis: A pseudomalignant clonal neoplasm characterized by USP gene rearrangements and spontaneous regression

摘要

Introduction: Nodular fasciitis (NF) is a rapidly growing, self-limited, myofibroblastic neoplasm that typically arises in subcutaneous tissues of young adults and regresses spontaneously. Nodular fasciitis mimics sarcoma on clinical, radiological, and histological grounds and is usually, diagnosed following excision.udCase Report: A 26-year-old female presented at surveillance computed tomography (CT) scan one year post-treatment for stage 1c ovarian dysgerminoma with a 4 cm axillary soft tissue mass, radiologically suspicious for metastasis with subclavian vein invasion. Histopathology of core biopsies favored NF, confirmed by detection of USP6 gene rearrangements by FISH analysis. This case describes an unusual relatively deep NF, suspicious for metastasis on CT scan with confirmed spontaneous regression over two years.udConclusion: Nodular fasciitis should be considered in the differential diagnosis of rapidly growing enhancing soft tissue masses. Molecular cytogenetic testing of USP6 gene rearrangements allows definitive diagnosis on core biopsies in challenging cases, permitting a conservative approach and avoiding potentially radical and unnecessary surgery.