Complete Spontaneous Regression of Lung Metastases after Resection of CIC-Rearranged Sarcoma: A Case Report

The vast majority of patients with soft tissue sarcomas (STS) of the trunk and bilateral lung metastases at diagnosis are considered incurable. These tumors have poor prognosis as only a palliative therapeutic approach can be offered to patients. We report on an extremely rare case in which bilateral lung metastases disappeared spontaneously following surgical resection of the primary CIC-rearranged sarcoma with no addition of chemotherapy or any other systemic therapy. A 53-year-old female presented with a rapidly swelling mass on her back. A magnetic resonance imaging scan of the chest revealed a large soft tissue mass on the posterior chest wall and bilateral lung metastases. Soon after stereotactic core-needle biopsy confirmation of round-cell sarcoma, the patient underwent surgery of the primary tumor as it started to be increasingly symptomatic. The resected specimen was pathologically diagnosed a poorly differentiated grade 3 sarcoma. Approximately 1 month later, a new CT scan revealed that the lung metastases were smaller and some of them had completely disappeared. Shortly afterward, the patient started adjuvant external beam radiotherapy of the tumor bed for 14 months. During the last follow-up visit, the patient confirmed no evidence of disease for 35 months postoperatively. In parallel, a histological study of pulmonary nodules, molecular analyses of the tumor, and a comprehensive study of the patient's immunophenotype were performed to gain some additional insights in the potential causes of this rare phenomenon.