A Case of Complete Abscopal Response in High-Grade Pleiomorphic Sarcoma Treated with Radiotherapy Alone

Background: “Abscopal response” refers to the spontaneous involution of untreated metastatic disease following local primary tumor-directed therapy. We report a case of an abscopal response of untreated lung metastasis in a man with pleomorphic sarcoma of the head and neck treated with hypofractionated radiotherapy. Methods: An inoperable pleomorphic sarcoma of the postauricular soft tissue was treated with 40 Gy of radiation in eight fractions. Untreated disease in the lungs was followed with CT scans. Results: At the two-month post-treatment follow-up, clinical exam and restaging CT demonstrated complete primary tumor involution. Additionally, CT chest images showed a dramatic disease response in the untreated pulmonary disease, which progressed to complete and persistent clinical response at one-year post-treatment follow-up. Conclusions: We report the first described case of a complete abscopal resolution of untreated lung metastases in a patient with a primary pleomorphic sarcoma of the head and neck treated with hypofractionated radiotherapy.