Abstract: Composite hemangioendothelioma is a rare vascular neoplasm of intermediate malignant potential,with an annual incidence of less than 0.1 per million,predominantly occurring in the deep soft tissues of the extremities and trunk.Clinically,it typically manifests as a slowly enlarging,painless mass.Magnetic resonance imaging reveals heterogeneous hyperintensity on T2-weighted images with infiltrative margins,while definitive diagnosis relies on histopathological examination.Histologically,the lesion is characterized by a composite admixture of at least two distinct vascular tumor components of varying differentiation.Immunohistochemically,the tumor cells commonly express CD34,CD31,ERG,and SMA.The disease exhibits locally aggressive behavior with rare distant metastasis,though splenic and osseous metastases have been documented.Wide local excision with a recommended surgical margin of ≥2cm remains the mainstay of treatment.Long-term postoperative surveillance with imaging is mandatory,focusing on the detection of local recurrence and regional lymph node involvement.At the time of this report,the patient remains free of recurrence and metastasis.

Key words: composite hemangioendothelioma, pathological features, immunohistochemistry, invasiveness