RESUMEN
BACKGROUND: Leiomyosarcoma is a malignant tumor that originates in smooth muscle cells and is rarely found in the oral cavity. We present a case of high-grade primary leiomyosarcoma in the mandible and discuss the diagnosis process. METHODS: The patient was a 64-year-old white man who had a slight increase in volume in the left-side mandible with a radiolucent osteolytic image with the destruction of the mandibular cortex. Incisional biopsy and preoperative examination were performed, including cone beam CT and examination by immunohistochemistry that defined the histologic diagnosis of leiomyosarcoma. The patient underwent reconstruction with an osteocutaneous flap with microvascular anastomosis. RESULTS: Two years after the surgery, there was no sign of recurrence of the lesion. CONCLUSION: The use of cone beam CT to define the limits of the lesion and the immunohistochemical findings were essential to establish the treatment plan.