With less than 40 cases reported, primary leiomyosarcoma is an extremely rare form of breast cancer (less than 0.0006% of cases) with unpredictable biological behavior that usually presents as a slow growing, mobile mass in middle age women. Most cases are low-grade and are cured by complete excision with wide margins. After surgical resection, late local recurrence and distant hematogenous metastasis to lungs and liver is, however, well-documented. To the best of our knowledge, bone metastasis has never been reported. Here we present a case of primary leiomyosarcoma of the breast metastatic to the femur.