Depicting Characteristic Staghorn Vessels in Solitary Fibrous Tumor of the Liver With Contrast-Enhanced Ultrasound and Ultrasound Localized Microscopy: A Case Report.

BACKGROUND Solitary fibrous tumor of the liver (SFTL) is a rare mesenchymal neoplasm. Most patients are asymptomatic, and lesions are discovered accidentally. Lacking specific imaging manifestations, SFTL is prone to misdiagnosis, making accurate preoperative diagnosis vital for clinical treatment. Thus, multimodal imaging is indispensable for preoperative evaluation. CASE REPORT We report the case of a 55-year-old woman with an asymptomatic liver mass identified during a routine health examination. Initial contrast-enhanced ultrasound (CEUS) revealed a hypervascular lesion with abundant peripheral blood flow and distinct intratumoral tortuous vascular signals. To further characterize these findings, ultrasound localized microscopy (ULM) was employed. This advanced imaging technique vividly delineated the characteristic "staghorn-shaped" branching vessels within the tumor, providing a pivotal preoperative clue highly suggestive of SFTL. Preoperative multi‑modality imaging demonstrated that the tumor was hypervascular and located adjacent to the inferior vena cava, making direct resection highly risky. In view of its hypervascularity and unfavorable anatomical location, neoadjuvant transarterial chemoembolization (TACE) was performed preoperatively to reduce tumor volume. This downsizing successfully transformed a potentially high-risk resection into a feasible procedure, enabling a subsequent safe and margin-negative surgical resection. Histopathological examination of the resected specimen confirmed the diagnosis of SFTL and corroborated the presence of the characteristic staghorn vascular pattern observed on imaging. CONCLUSIONS In conclusion, combined CEUS and ULM effectively displays characteristic vascular signs of SFTL to assist differential diagnosis. Preoperative TACE is an effective neoadjuvant approach for anatomically difficult SFTL to facilitate radical surgery. Further large-sample long-term follow-up studies are needed to verify the conclusions, due to limited single-case data.