Benign soft-tissue masses drastically outnumber malignant tumors. Both benign and malignant soft-tissue masses can present in the same manner, as a painless growing soft-tissue lump or bump. The implications of misdiagnosing a soft-tissue sarcoma can be devastating. The most common mistake occurs when all masses are assumed to be lipomas. A careful history, physical examination, and appropriate imaging can determine the benign or malignant nature of a tumor. A mass that is large (>5 cm), deep (in relation to investing fascia), and firmer than the surrounding muscle should raise suspicion for a malignancy. Small, superficial masses are more likely to be benign, but up to 32% of soft-tissue sarcomas can present in this manner. The orthopaedic surgeon should be able to recognize common imaging findings for benign and malignant entities.