Primary undifferentiated pleomorphic sarcoma in oral-maxillary area: retrospective study and molecular analysis.

Undifferentiated pleomorphic sarcoma (UPS) in oral-maxillary area is rarely reported. Herein, we aimed to investigate the clinical characteristics, treatment strategies, prognosis, and molecular features of the oral-maxillary UPS. In total, 10 cases with primary oral-maxillary UPS were included. The rapidly progressive UPS can easily develop to an advanced and life-threatening stage, especially concerning the complex anatomical structures and spaces in the oral-maxillary area. The final diagnosis for UPS greatly depended on histological findings and immunohistochemistry staining after the exclusion of all possible differential diagnoses. Retrospectively, the treatment strategies for the included cases still referred to those of oral squamous cell carcinoma (OSCC). Statistically, the median overall survival (OS) for all the included cases was 7.75 months (range: 5-17 months). Comparatively, 3 cases had improved OS (median survival: 17 months, range: 17-18 months) and experienced PR/SD with neoadjuvant chemotherapy (anlotinib). The molecular features were demonstrated by using whole exonic sequencing for 1 included case. Cancer driver gene detection revealed GBP4 as a candidate driver gene for the primary oral-maxillary UPS. Additionally, a missense mutation in gene PIK3CA (p.E545K) was also identified. Our findings could greatly expand the knowledge about primary oral-maxillary UPS, and provide molecular evidences to improve the therapeutic options for primary oral-maxillary UPS.