Leiomyosarcoma of the Mandible

Leiomyosarcoma (LMS) is a soft tissue sarcoma arising from the embryonic mesoderm of smooth muscle lineage. LMS of the oral cavity is exceedingly rare, accounting for less than 1% of smooth muscle malignancies. We describe a 60-year-old female who presented for evaluation of a rapidly expanding mass in her lower left mandibular quadrant of three weeks duration. The patient reported a one-year history of sporadic pain in the area. The patient's medical history was significant for a lesion involving the same quadrant three months prior that was diagnosed as a myofibroma. Clinical examination revealed a large, exophytic, fleshy, erythematous mass extruding from the left posterior mandible. Cone beam computed tomography demonstrated a multilobulated hypodensity involving the left mandibular body and ramus. The lesion had perforated the buccal and lingual cortices, displaced tooth #19 in an anterior-buccal direction, and inverted its vertical orientation. A left hemimandibulectomy was performed, and histopathologic examination of the resection specimen showed an infiltrative hypercellular proliferation of atypical spindle cells with distinctly eosinophilic cytoplasm, cigar-shaped nuclei, and a fascicular growth pattern. The spindle cells demonstrated immunoreactivity to desmin and caldesmon, supporting a diagnosis of LMS. Immunohistochemical staining was also positive for ER, PR, and patchy WT1, suggesting the possibility of a gynecological origin. A uterine primary was discovered on subsequent medical evaluation. The patient is currently undergoing chemotherapy for the management of metastatic uterine LMS. Less than twenty cases of metastatic LMS have been reported in the literature to date. Knowledge of the morphological and immunohistochemical hallmarks of this malignancy can aid in directing the diagnostic workup, thereby facilitating timely management. Furthermore, this challenging case highlights the importance of effective interdisciplinary communication in reconciling discrepancies that arise between the histologic diagnosis and clinical behavior of a lesion.