Primary Sternal Leiomyosarcoma.

We report the case of a primary leiomyosarcoma of the sternum in a 70-year-old man that was discovered incidentally during prostate cancer staging with positron emission tomography combined with computed tomography. Interventional radiology biopsied the lesion; pathologic examination showed spindle cells, indicating probable leiomyosarcoma. No primary site was found on contrast computed tomography, thus suggesting that the tumor was primary rather than metastatic. Given the tumor's location and mortality risk, the patient underwent a sternotomy and reconstruction with methyl methacrylate, followed by an uneventful recovery. This case underlines a rare leiomyosarcoma presentation, constituting less than 0.7% of all primary malignant bone tumors, noted for its unusual location and rarity.