Distant Tumor Response in the Pelvis After Histotripsy of a Metastatic Sarcoma of the Liver in a Patient With Differentiated Liposarcoma.

Dedifferentiated liposarcoma with leiomyosarcomatous differentiation is a rare, aggressive subtype of soft tissue sarcoma with limited treatment options. Histotripsy is a novel, non-invasive, non-thermal ablative therapy that uses focused ultrasound to induce mechanical tissue destruction through acoustic cavitation. We report a case of a 72-year-old female with metastatic dedifferentiated liposarcoma who underwent histotripsy for 2 large hepatic metastases after progression on other therapies. Partial liquefaction of tumors was observed on post-procedural imaging. Following a second histotripsy session targeting additional hepatic lesions, imaging demonstrated significant tumor destruction, and a concurrent reduction in the size of an untreated pelvic metastasis was noted. No other therapy was administered during this period. Symptomatic improvement with reduction in abdominal pain and pressure was achieved. However, tumor regrowth was observed at 5 months post-treatment. This case demonstrates the potential of histotripsy to achieve local tumor control and symptomatic relief, with a possible systemic effect on distant metastases.