Abstract
Undifferentiated pleomorphic sarcoma (UPS) is a high-grade neoplasm that is usually located in the extremities and retroperitoneum. In the past, UPS was considered the most common soft tissue sarcoma in adults; due to improvements in diagnostic techniques, most cases have been reclassified as other lineage-specific tumors. Gnathic bones are rarely affected, and the clinicopathological characteristics of this neoplasm when diagnosed in the jaw remain to be better described. In this report, we present a rare case of mandibular UPS affecting an 88-year-old female who demonstrated a painful swelling on the right side of the mandible that was accompanied by a pathological fracture. Microscopic examination revealed a pleomorphic spindlecell neoplasm with mitotic figures and necrosis. The patient underwent surgery and adjuvant radiotherapy but experienced metastasis after 12 months of follow-up and died. Diagnosis of UPS is challenging, and oral pathologists must be aware of this entity when dealing with aggressive undifferentiated neoplasms.