Background: Undifferentiated uterine sarcomas are rare malignancies often presenting at advanced stage. Case: A female in her ninth decade presented to our MEDCEN emergency department complaining of onset of severe right arm pain while performing activities of daily living. A pathologic humeral fracture was diagnosed and subsequent orthopedic evaluation resulted in a biopsy and placement of her arm in a cooptation splint and sling. An abdominal exam revealed a 10-cm mass in the right lower quadrant that was thought to originate from the uterus. Computed tomography imaging was concerning for a primary endometrial process and she was referred to gynecologic oncology. Her humeral biopsy was consistent with a poorly differentiated metastatic sarcoma. An endometrial biopsy was consistent with undifferentiated uterine sarcoma, the origin of her humeral lesion. Conclusion: Humeral metastasis is an uncommon presentation for undifferentiated endometrial sarcomas.