(1) Background: This retrospective study aimed to analyze the history and treatment outcomes of localized, high-grade MLS of the extremities. (2) Methods: We retrospectively reviewed 82 patients with primary high-grade MLS of the extremities. OS, LRFS, MFS, PRS, and DFS were analyzed. (3) Results: Five-year OS and LRS were 96% (95% CI: 86–98) and 94% (95% CI: 85–98), respectively. Statistical analysis indicated no risk factors for OS and LFRS. MFS was 77% (65–85) at 5-year follow-up. Size (p = 0.0337) was the only risk factor statistically significant for MFS (HR = 0.248, 95% CI: 0.07–0.84). Median PRS after distant metastasis was 34 months (range: 1–127 months). Five-year PRS was 79% (48–93). Overall, the 5-year DFS was 76% (65–85). (4) Conclusions: Patients with MLS were found to have a good prognosis. In high-grade deep-seated tumors, common risk factors for MLS do not correlate with survival. Tumor size appears to be the only predictor of long-term DSF and MSF.