A Novel Gene Fusion in Pediatric Angiosarcoma of Pelvic soft Tissue: A Case Report and Literature Review.

Pediatric angiosarcoma of soft tissue, an extremely rare entity, remains poorly understood from a genetic standpoint. Herein, we present the case of a previously healthy 17-year-old girl with acute left hip pain. Subsequent magnetic resonance imaging revealed a 21.8 cm left pelvic sidewall mass with heterogeneous enhancement and multiple lung nodules. Biopsy of the tumor showed an infiltrative, hemorrhagic neoplasm composed primarily of atypical spindle to epithelioid cells. Focal vasoformative architecture was appreciated. Immunohistochemically, the tumor cells were strongly positive for CD31, ERG, and FLI-1, supporting the diagnosis of angiosarcoma. Genetic analysis identified a novel gene fusion. belongs to the angiopoietin receptor family, and its fusion with is predicted to mediate tumorigenesis. This report expands the current knowledge on the spectrum of gene rearrangements of angiosarcoma.