Significant increase in calcification and ossification observed after the second relapse of low-grade myofibroblast sarcoma treated with radiotherapy followed by anlotinib and toripalimab: a case report.

Introduction: Low-grade myofibroblastic sarcoma (LGMS) is a rare malignant neoplasm of the soft tissues, originating from stromal cells and accounting for approximately 1% of all malignant soft tissue tumors. It is characterized by its invasive nature, high rates of recurrence, and the presence of calcification. To date, no established treatment strategy exists for relapsed LGMS. This study aims to provide a case treated with combination regimen of palliative radiotherapy followed by toripalimab and anlotinib for LGMS patients with the second relapse, to evaluate its efficacy and safety, and to explore the impact of tumor calcification and ossification on subsequent treatment outcomes and prognosis. Methods: This report presents the case of a 23-year-old male LGMS patient with two relapses who initially presented with post-tracheotomy status due to pharyngeal obstruction caused by masses located at the base of the tongue and floor of the mouth that had persisted for 3 weeks. He underwent palliative radiotherapy followed by toripalimab combined with anlotinib. Subsequently, surgical resection of residual lesions performed. Results: CT imaging demonstrated a significant increase in calcification and ossification of the second relapsed lesions and lymph nodes in the draining region, and stable disease with tumor shrinkage to these interventions of palliative radiotherapy followed by toripalimab combined with anlotinib. The patient was followed up until February 2025, achieving a progression-free survival 2 of 48 months from initiation of radiotherapy and an overall survival of 9 years. Discussion: Based on this case report, palliative radiotherapy followed by anlotinib and toripalimab may yield an acceptable therapeutic effect while being associated with manageable treatment-related adverse events in LGMS patients experiencing two relapses, who have previously undergone targeted therapy using vascular endothelial growth factor receptor-tyrosine kinase inhibitors and have not received prior radiotherapy. Nevertheless, this hypothesis requires further validation through higher-level evidence-based medical research.